In India, starting in the 7th century BC, a group of forest philosophers engaged in debates to discover the essence of who we are, which they called atman (the self). Their investigation soon pointed to an inner reality beyond the senses, which we might today call the unconscious. Our atman, they claimed, was not composed of our thoughts (which are fleeting), but was equal to the source producing them. And since this source cannot be known directly, it is the ultimate mystery of every human being.
During their search, they also stumbled upon what they claimed to be an eternal truth, namely that atman, in its purest form, is equal to the essence of the universe itself. The realization of this truth, they claimed, allowed yogis to escape the eternal cycle of reincarnation and experience eternal bliss in the afterlife. These esoteric ideas became the foundational concepts of Eastern philosophy. We will trace this tradition in the following chapters.
Around 2600 BC, in the Indus Valley in modern-day Pakistan, a number of small villages grew into cities, which together formed the Indus Valley Civilization. In its main cities, Harappa and Mohenjo Daro, we do not find palaces or temples, but we do find beautiful baths, lined with bitumen and surrounded by colonnades (see Fig. 215). We also find a regular grid of streets and houses built from standardized bricks. Houses had toilets and baths, and waste water was routed to a sewage system beneath paved streets. The Indus Civilization also traded with Mesopotamia, as we have found Indian goods in the Middle East and vice versa. They also developed their own writing system, although it has not yet been deciphered.
Fig. 215 – The Great Bath of Mohenjo Daro in Pakistan (Saqib Qayyum, CC BY-SA 3.0)
Fig. 216 – A bust from the same city (Mamoon Mengal, CC BY-SA 1.0; National Museum of Pakistan)
A seal found in Mohenjo Daro depicts what might be a three-headed figure in yoga posture (see Fig. 217), which would become a popular image in later Hinduism (see Fig. 218). If we are reading this seal correctly, it could mean that some aspects of Hinduism, including yoga itself, have roots in this ancient civilization. Unfortunately, we don’t have enough evidence to prove this assertion.
Fig. 217 – Possibly a three-headed god in yoga posture from Mohenjo-Daro (c. 2000 BC)
Fig. 218 – The three-headed god Brahma in yoga posture (700 AD) (Sailko, CC BY-SA 4.0)
The cities of the Indus Valley started to decline around 1700 BC and were gradually abandoned over the next few centuries. The cause seems to have been regional climate change, for the Indus River shifted course, and another nearby river dried up. As a result, the land around the settlements became dry, incapable of sustaining high-level agriculture.
The Indo-Europeans, whom we met in the previous chapter, entered India around 1500 BC. They called themselves Aryans (“the noble ones”). As was true of all early Indo-European tribes, they were nomads who left few archeological remains. In their sacred text, the Rig Veda (which we will discuss in more detail shortly), we read that their enemies, called the Dasyus, lived in walled forts and were subdued by the Aryans after heavy fighting. For instance, the Aryan King Divodasa is described as defeating the Dasa ruler Shambara, who had many mountain fortresses. The god Indra is also called “the slayer of Dasyus,” and is given credit for their defeat:
He […] who drove the race of Dasas down into obscurity, who took away the flourishing wealth of the enemy as a winning gambler takes the stake—he, my people, is Indra. 
The Dasyus are described as dark-skinned, leading some to speculate they were the original inhabitants of India, perhaps related to people of the Indus Valley Civilization.
Although the archeological record is meager, the Aryans did produce four huge religious texts, called the Vedas, which at the time were transmitted orally. The word “veda” is related to the Proto-Indo-European root “ueid,” which both means “to see” and “to know.” It is also related to the Latin word “videre” (“to see”) and the modern English “video.” The oldest and most important of these texts is the Rig-Veda (“rig” meaning “praise”), which contains 1028 hymns in praise of the gods. The oldest of these hymns were written around 1500 BC, when the Aryans reached the Punjab region in northern India (as evidenced by flora and fauna mentioned in these hymns). These early hymns describe the Aryans as cow herders and warriors that operated in separate clans. The other three Vedas were written later, likely between 1200 and 900 BC. Near the end of this period, the Aryans had entered the Ganges Valley.
The purpose of these hymns was to attain the favor of the gods in the hopes of gaining rewards, such as wealth and protection. Take, for instance, the following verse:
You [the gods] are worthy of praise and of sacrifice, you thirty-three gods of Manu [the first man], arrogant and powerful. Protect us, help us and speak for us; do not lead us into the distance far away from the path of our father Manu. You gods who are all here and who belong to all men, give far-reaching shelter to us and to our cows and horses. 
The simplicity of their approach to religion is also beautifully depicted in the following line from the Rig-Veda:
The singer of my praise will never be without cows. 
The syllables of the Vedas, when spoken out loud, were considered sacred and powerful. It was believed that they were not a human product but had been heard (sruti) by rishi’s, or inspired poet-seers. As a result, only the priests, called brahmin, were allowed to chant these hymns during their rituals. The most important ritual was a sacrifice, which was paid for by a wealthy patron from the aristocracy and performed by a group of priests. The Hotr priest was responsible for reciting the Rig Veda, the Adhvaryu priest was responsible for preparing the sacrificial ground, building fire pits, killing a sacrificial animal, cooking the offerings, and throwing offerings into the sacred fire, and the Udgatr priest was responsible for singing. Another priest, called Brahman, observed the ritual in silence and only intervened to set right any mistakes.
The Vedas are often considered to be the founding texts of Hinduism, but they are in many ways far removed from what we would today associate with the religion. For instance, the texts do not express the desire to renounce the material world in favor of a spiritual quest and the texts also rarely mention the major gods of later Hinduism. Vishnu is mentioned only a few times. Shiva only appears as an epithet of several other gods, including the god Rudra, with whom he was later identified. Brahma is not mentioned at all, although he later became identified with the creator Vedic god Prajapati.
The most mentioned god of the Rig-Veda is Indra, who, in his war chariot, battled the water serpent Vritra. According to the story, Vritra had caused a great drought by swallowing all the water of the earth. Aided by the sacrifices and hymns of humans, Indra killed the monster with his thunderbolt (vajra). We read:
Like a [strong] bull, he took to himself the Soma [a divine hallucinatory drink], drank the pressed drink from three mighty bowls, picked up his weapon, the fiery thunderbolt, and slew the first-born [monster].
Footless, handless, [the serpent] gave battle to Indra, who flung the thunderbolt into his back. […] Vritra lay scattered in many places [...] like a slaughtered offering [and over him] the flood of the waters climbed, which he, by his might, had formerly enclosed. Beneath its course, now, the great dragon lay. 
The fire-god Agni also appears frequently. He was equated with the sacred fire that was lit by brahmins on their mud altars. During their rituals, the priests fed plants, animals, and butter to the fire, which were swallowed up by Agni and ended up as food for the gods. Agni also was the cremation fire, in which the corpses of the dead were sacrificed.
The sacred heat generated by the fire was called tapas and was considered very powerful. It was also equated with the inner heat generated by the body, especially during ritual activity (and in later centuries also during meditation). We even read in the Rig Vedas that the “inspired poets […] became invincible through tapas.”
Another popular god was Soma, which is also the name of a plant from which a liquor could be made that induced altered states of consciousness. In one of the hymns, a god recorded the experience as follows:
Like impetuous winds, the drinks have lifted me up. Have I not drunk Soma? […] In my vastness, I surpassed the sky and this vast earth. Have I not drunk Soma. 
One of its qualities was that it made the drinker feel immortal. Indra drank it to generate tapas within himself to be able to kill Vritra and, in another verse, the drink transported him to a “world where light shines, where immortals live, where the god of death Yama dwells, and where there is joy and pleasure.” In another verse, we read that soma was divine and was brought down from heaven to mankind by Indra flying on an eagle. On earth, it became “the offering loved by the gods.” We know the liquid was pressed out of a plant with stones, but the precise plant has yet to be identified. In fact, even in Late Vedic days the plant was already hard to obtain and was sometimes substituted for another.
The sky-god Varuna is only mentioned a few times. The name of this god is derived from the root “vr,” which means “to cover” or “to encompass,” for he was believed to encompass the entire universe. The god Varuna was believed to be responsible for rta, which is the force that gives order to the universe. Similar to the Egyptian and Mesopotamian idea of a cosmic order, it was believed that rta made the heavenly bodies take their proper courses, made the seasons come and go, and also made society function in an orderly way. The rta associated with social customs was called dharma. In this role, Varuna watched the deeds of men and punished those who violated rta.
Despite these far-reaching powers, almost no one ever prayed to either rta or Varuna. We find something similar in Greece, where the sky-god Uranus received little attention and no worship. According to one hypothesis, Varuna and Uranus were older gods who were in time replaced by the new warrior god-kings Indra and Zeus. These new gods were much easier to please through praise and offerings and, therefore, might have appealed more to the pragmatic warrior-folk.
Another important concept from the Vedas is Brahman, which in the Rig-Veda refers to the power in the sounds of the syllables of Veda. Eventually, however, the word came to be equated with the essence of the universe.
The Vedas also describe various ideas about the afterlife. Some hymns claim that the souls of the deceased join the forefathers in heaven, while others claim they will go to a house of clay ruled by the god of death (a Mesopotamian idea). In other places, we read that the soul simply disperses along with the body among the elements.
Creation stories also appear in various forms. The most interesting version starts with a paradox and finally concludes that the universe emerged out of nothing through the power of tapas. We read:
There was neither non-existence nor existence then; there was neither the realm of space nor the sky which is beyond. […] There was neither death nor immortality then. There was no distinguishing sign of night and day. That one breathed, windless, by its own impulse. Other than that there was nothing beyond. […] The life force that was covered with emptiness, that one arose through the power of heat [tapas]. 
Interestingly, the text then reveals that even the gods do not have all the answers:
From where this creation has arisen—perhaps it formed itself, or perhaps it did not—the one who looks down on it, in the highest heaven, only he knows—or perhaps he does not know. 
How is it that even the gods might not know? The text explains that “the gods came [after] the creation of the universe” and, therefore, “[no one] knows from where it has arisen.” It would remain a common motive in Hinduism that the gods are bound by the universe and its laws and are therefore inferior to this deeper mystery.
In another hymn, we read that the universe was created out of the word “AUM,” which was considered a powerful mantra that was frequently chanted during rituals. The later texts called the Upanishads even equated “AUM” with the entire world.
Fig. 219 – The symbol for AUM as it appeared in written form in the first centuries AD.
In a later Vedic hymn, we read that the universe was created out of the sacrifice of the primordial being Purusha, who was ritually dismembered by the gods (another appearance of the Neolithic dying-and-resurrecting god):
The gods, performing the sacrifice, bound the Man as the sacrificial beast. 
Purusha was considered divine, and as a result, the material world in Indian mythology is considered divine as well. As a result, Purusha was not only the sacrificial victim, but also the divinity to whom the sacrifice was dedicated. We read:
With the sacrifice the gods sacrificed to the sacrifice. 
After the being was killed, the gods used the various parts of his body to create both the world and society. This creation story also sought to explain the creation of the four castes of India, which had formed during the late Vedic period when the communities had become more hierarchical. Created from his mouth were brahmins, from his arms the kshatriya (the rulers), from his thighs the vaishya (the middle class), and from his feet the shudra (those who served the other orders). Cleverly, the Brahmins placed themselves on top of this hierarchy.
Between 800 and 600 BC, a number of texts known as the Brahmanas were written, which mainly elaborate on the execution and meaning of the Vedic rituals. The writers of the Brahmanas were also interested in overcoming death. They wrote that through sacrifice, men could achieve immortality in heaven. Some brahmins even claimed that through sacrifice, they could gain the power to force the gods into submission. A skilled brahmin, they claimed, could control the gods, or even become a god himself. The Brahmanas also spoke of a recurring death, which they considered especially dreadful. This idea, although not expanded upon, appears to be an early belief in reincarnation. We read in cryptic language:
When they die, they come to life again, but they become the food of this [Death] again and again. 
Also starting around 800 BC, urbanization reappeared in India and hundreds of small kingdoms formed. As the economy grew, altars also became more sophisticated. Instead of mud, they were now made of bricks. Altars could have various geometric shapes, including a square, a circle, or a semi-circle. The mathematician Baudhayana (c. 7th century BC), in texts called the Baudhayana Sutras, worked out the exact proportions of these altars. While figuring out how to build a square altar with exactly the area of two smaller square altars, he stumbled on the Pythagorean theorem (see Fig. 220). He described it as follows:
The areas [of the squares] produced separately by the lengths and the breadth of a rectangle together equal the area [of the square] produced by the diagonal. 
Although the Pythagorean rule had been in use in both Egypt and Mesopotamia since about 1800 BC, this is the first explicit statement of the general theorem in world history.
Fig. 220 – According to the Pythagorean theorem, the squares a2 + b2 are equal in are to the square c2. Baudhayana used this to construct an altar (c2) with an area equal to two other alters (a2 and b2).
Baudhayana also found a method to construct a circular altar with approximately the same area as a square—a process known as squaring the circle, which required him to use a rough estimate of pi. He also gave a good approximation of the square root of two accurate to five decimal places (1.4142). Unfortunately, early Indian mathematical texts rarely gave proofs for their theorems, so we can often only guess how Baudhayana made these discoveries.
Both the Vedas and the Brahmanas describe curious individuals who did not take part in society. We read of vratyas (“people who have taken vows”), who practiced flagellation and other forms of self-mortification. The Brahmanas associate these people with the god Rudra, the master of poisons, medicine, and mind-altering drugs, and depict them as ascetics roaming about in an intoxicated state. They also speak of them as physicians and guardians of truth. In the Rig Veda, we also read of a long-haired ascetic who wandered homelessly and entered the spiritual world drinking a drug from the cup of Rudra. We read:
Long-hair holds fire, holds the drug, holds sky and earth. Long-hair reveals everything, so that everyone can see the sun. Long-hair declares the light. These ascetics, swathed in wind [naked], put dirty orange rags on. When gods enter them, they ride with the rush of the wind. “Crazy with asceticism, we have mounted the wind. Our bodies are all you mere mortals can see.” He sails through the air, looking down on all shapes below. The ascetic is a friend to this god and that god, devoted to what is well done. […] The wind has churned [the drug] up; Kunamnama [an otherwise unknown female deity] prepared it for him. Long-hair drinks from the cup, sharing the drug with Rudra. 
This could be an early description of a yogi. It is unknown whether these people were fellow Aryans or whether they came from the native populations, perhaps linking all the way back to the Indus civilization.
The growing economy eventually gave people enough leisure time to engage in philosophical and theological debate and to travel long distances to seek out the great teachers of the day. From the 7th century BC, these developments caused a revolutionary turn in Hinduism. Instead of relying on communal rituals, a number of philosophers “departed into the forest” and investigated the inner world. Although the old Vedic rituals remained important, they were now given a new spin, as these new thinkers claimed that the true sacrifice should be “offered internally” for the purpose of “seeking […] the self (atman).”  This search was recorded in the form of debates and teachings in a series of texts called the Upanishads (which literally meant “to sit beside,” referring to a student sitting next to his teacher). The oldest of these texts are the Brihadaranyaka (“Great Forest”) Upanishad and the Chandogya (“Poetic Rhythm”) Upanishad from the 7th or 6th century BC. The general inquisitive attitude in the Upanishads is nicely captured by the following lines:
These immensely learned householders got together once and began a deep examination of these questions: “What is our self (atman)? What is the essence of the universe (brahman)?” 
These discussions were often sponsored by wealthy patrons, who held competitions rewarding the philosopher with the best answer with cows, the most valued commodity of the day:
We’ll give you a thousand cows for such a speech! 
Some followers of this new spiritual path became renouncers, who deliberately left behind their house, their family, and their possessions, and instead became wandering ascetics. They believed that the self cannot be found in the mundane life of the family, but instead required one to retreat into the forest, undistracted by the sensual pleasures of life:
It is when they come to know this self that Brahmins give up the desire for sons, the desire for wealth, and the desire for worlds, and undertake the mendicant life. 
These renouncers became the ideal of India’s spiritual quest.
But not all philosophers left behind the everyday world. Some continued to be married and some even became the personal philosophers of kings. There were even a few renowned philosophers who were not from the brahmin caste, but from the aristocracy, such as the philosopher-king Pravahana Jaivali, who claimed to be in possession of knowledge that “had never reached the Brahmins.”
One of their greatest achievements was their discovery of what we today call the unconscious—the space inside of us from which our thoughts and feelings arise. How did they achieve this? The forest philosophers were interested in the capabilities of the soul, which, to them, included breathing, thinking, speech, sight, and hearing. The next step was to find the source of these functions, which they identified as the self (atman, which originally meant “the breath of life”). The atman, they believed, is the space inside of ourselves that remains even when we do not think or feel. It is the thinker behind the scenes who produces our thoughts. There was a problem, however. We humans are only conscious of what can be described in terms of sensory data—that is, our thoughts. And since the source of these thoughts is not itself a thought, we cannot be aware of it. It is literally beyond the senses and therefore can’t be put into words. Or as we read in the Kena Upanishad:
There the eyes goes not, speech goes not, nor the mind. 
All we can say about atman was what it was not:
About this atman, one can only say that it is not this and it is not that. 
As the sage Yajnavalkya (c. 7th century BC) rightly concluded, atman cannot be known in the same way we can know an object such as a horse or a cow, since we “cannot see the seer who does the seeing; [we] can’t hear the hearer who does the hearing; [we] can’t think of the thinker who does the thinking; and [we] can’t perceive the perceiver who does the perceiving.” Or phrased differently:
The one who is aware: “Let me say this”—that is atman. The faculty of speech enables him to speak. The one is aware: “Let me listen to this”—that is atman. The faculty of hearing enables him to hear. The one who is aware: “Let me think about this”—that is atman. The mind is his divine faculty of sight. 
Then the forest philosophers pushed their argument further. Since atman cannot be described, it must be a reality without properties, and since something with no properties cannot change, it followed that this reality must be eternal. Consequently, an immortal reality must exist within each of us. It is for this reason that they claimed that the self “is the one who is beyond hunger and thirst, sorrow and delusion, old age and death.” Discovering this ultimate reality within ourselves became the principal goal.
The Indian identification of the self with the unconscious (versus the identification of the self with the ego in the West) has caused the most important distinctions between Eastern and Western philosophy. A culture that identifies itself with the ego is likely to develop a strong concern for the individual and its unique destiny. In contrast, a culture that identifies itself with a formless reality—one that is the same in all of us—is likely to value our oneness with each other and with the universe. Much of the different paths of East and West have hinged on this simple difference in the identification of the self.
Fig. 221 – Depiction of the renouncer Jaimuni questioning sage Markandeya (c. 1785 AD)
The interest in the mystery of the self was so all-consuming for the Indian forest philosophers that they gave it cosmic significance. When investigating brahman (the fundamental reality or essence of the universe), they found at its root the same indescribable mystery which they had found when studying atman. From this observation, they made the leap that atman and brahman were equal. This became the most important conclusion of the Upanishads:
The atman is the brahman. That is the teaching.
This cosmic connection, they claimed, was hidden from ordinary people. It was secret knowledge (another meaning of the word “upanishad”).
The teaching that brahman is atman is beautifully explained by the sage Uddalaka (c. 7th century BC), who was the personal philosopher of a local king and later became a renouncer. In the Chandogya Upanishad, we read how he taught his son Svetaketu:
AUM! There was [a boy named] Svetaketu Aruneya, and his father said to him, “Svetaketu, go live as a seeker of Brahman! […]” Having become a pupil at twelve and having studied all the Vedas, he returned [home] at twenty-four, proud, conceited, thinking himself well-schooled. Then his father said to him: “Svetaketu, since you are proud and conceited, dear boy, and consider yourself learned, did you ask for that instruction by which that which is not heard, becomes heard, [that which is] not thought, becomes thought, and [that which is] not known becomes known?” “But in what manner, sir, is this teaching?” “Just as from a single lump of clay, dear boy, one would know just about everything made from clay, the difference being a mere verbal distinction, a name, the reality is only clay.” […] “Indeed, those worthy men did not know this, for if they had known it why did they not tell me? Sir, please tell it to me.” “Certainly, dear boy,” he replied. […]
“O Blessed One, instruct me further.” “Certainly, dear boy,” he replied. “Bring a fig from over there.” “Here it is, sir.” “Divide it.” “It is divided, sir.” “What do you see there?” “These rather small seeds, sir.” “Divide one.” “It is divided, sir.” “What do you see?” “Nothing, sir.” “Dear boy,” he said to him, “that finest essence which you do not perceive, from this very essence, dear boy, that great fig tree arises. Believe me, dear boy, that which is the finest essence, the whole universe has That as its Self. That is Reality, That is the Self (atman), and you, Svetaketu, are That!”
“O Blessed One, instruct me further.” “Certainly, dear boy,” he replied. “Place this salt in water, and in the morning come to me.” He did exactly so, and he said to him, “the salt that you put in the water last night, bring it hither.” But while he grasped for it he could not find it, since it had completely dissolved. “Take a sip from the edge of it. What is there?” “Salt.” “Take a sip from the middle. What is there?” “Salt.” “Take a sip from the far edge. What is there?” “Salt.” “Set it aside and come to me.” And [the boy] did exactly that, [saying] “It is always the same.” He said to him, “Being is indeed truly here, dear boy, but you do not perceive it here. That which is the finest essence, the whole universe has That as its Self. That is Reality, That is the Self, and you, Svetaketu, are That!” 
Since the forest philosophers believed all human beings were, in essence, equal to the universe itself, it followed that our feeling of separateness from each other must be an illusion (maya) brought on by our ignorance. Uddalaka concluded that in reality, one atman could not be distinguished from another, just as two rivers fusing into the same sea can no longer say, “I am that river. I am this river.” In Zen Buddhism, this idea is often described by comparing the mind to the surface of a pond. When wind blows across the surface, the reflection of the pond is broken into many fragments. However, if the wind ceases and the surface becomes still, the reflection turns into unity. The same will happen to the world, it was believed, when the mind becomes still.
Yajnavalkya used sleep as a metaphor to make the same point. When we are in deep dreamless sleep, we are not conscious, and therefore, there is “no second reality that [our mind] can see as something distinct and separate from [itself].” Instead, there is only the unity of atman, which he equated with the “world of brahman” and described as a state of pure “bliss.”
The philosopher-king Ajatashatru (c. 7th century BC) expanded on this analogy. He once offered a brahmin from the Gargya family a thousand cows for telling him about brahman. Gargya first claimed that brahman is equal to the sun, but the king was not satisfied. Then he tried the moon, lightning, wind, fire, and so on, until he finally fell silent. Then Ajatashatru stepped in and told him there was more to brahman. Upon hearing this, Gargya asked to be his student. As a demonstration, King Ajatashatru approached a sleeping man, woke him up, and asked Gargya:
“When this man was asleep here, where was the person consisting of perception? And where did he return?” Gargya did not know the answer. 
He then taught that when we dream, the cognitive powers which are normally distributed throughout the body are gathered in a cavity in the heart. This cavity was conceived of as a cosmic space in which people travel in their dreams. During deep dreamless sleep, he claimed, atman leaves the heart through thousands of veins and enters the pericardium, the sac surrounding the heart. In this place, the self is oblivious to everything. 
When a man sleeps, the person who consists of understanding rests in the space within the heart [...]. And when that person [has] absorbed the senses, one is said to be asleep. The breath is absorbed, the voice and the faculties of eye, ear, and intellect. And when a man thus sleeps, the whole world is his. He becomes a maharaja, as it were. He becomes a great Brahmin, as it were. […] For, just as a maharaja, taking with him his people, moves around in his own country as he pleases, so this person asleep, taking with him his senses, moves around in his own body as he pleases.
But when he is in deep dreamless sleep, knowing nothing at all, he is at rest throughout his body, having crept out of that space within the heart through 72,000 veins, which lead from the heart into the pericardium. He slips out of the heart through these veins and rests within the pericardium. He rests there oblivious to everything. […]
As a spider comes out along its thread or as sparks pour from a fire, even so, from atman come forth all the senses, the worlds, the gods, and all being. And the secret name (“upanishad”) thereof is the reality of reality (“satyasya satya”), since […] the self is the real behind the senses. 
Curiously, the same lesson—that the self is equal to the essence of the entire universe—which is here obtained through the study of sleep, was later gained through meditation (the writers of the early Upanishads seem not to have been aware of meditation). In recent times, MRI research has confirmed that experienced meditators can readily enter a state in which their sense of self is weakened, giving them a sense of becoming one with their environment (the same state can also be achieved with hallucinogens such as LSD). It is tempting to assume that these early forest philosophers had a similar experience when they practiced their ascetic practices (tapas) in the wilderness, but unfortunately, very little is told about what specifically they did. In some instances, the texts speak of a process of self-discovery, again, without going into detail how this was done. For instance, in the Chandogya Upanishad, we read that Indra goes to study under the creator god Prajapati in order to find the self. When Prajapati asked Indra what he was looking for, he stated:
Sir, people report these words of yours: “The self that is free from evils, free from old age and death, free from sorrow, free from hunger and thirst […]—that is the self that you should try to discover, that is the self that you should seek to perceive. When someone discovers that self and perceives it, he obtains all the worlds, and all his desires are fulfilled.” 
After 32 years of study, Prajapati offered Indra a false teaching of the self, claiming it to be equal to the visible body. Indra left triumphantly, but eventually discovered “the danger” of this belief, since the body eventually perishes. After another 32 years, Prajapati taught that the self is the person who moves around in dreams. Indra agreed that this person cannot be harmed in the same way as the body, but it can experience unpleasant sensations. He was then told that the self is found in the state of dreamless sleep, but this self cannot perceive anything. Finally, he learned the truth, identifying the self with the thinker that thinks our thoughts.
Fig. 222 – Yogis in the wilderness (c. 18th century)
Another radical conclusion directly followed from the equation of atman and brahman. Since the gods were also part of brahman, it follows that the gods were also part of the self. As a result, the gods came to play an inferior role to atman. In the Brihadaranyaka Upanishad, we read:
If a person knows “I am brahman,” he becomes the whole world, and not even the gods can prevent his becoming thus, for he becomes their very self. So, when a man venerates another deity, thinking, “He is one and I am another,” he does not understand. […] The gods […] are not pleased at the prospect of men coming to understand this. 
Or in the words of Yajnavalkya:
May the gods forsake anyone who considers the gods to reside in something other than his self.
This very self is the lord and king of all beings. As all the spokes are fastened to the hub and the rim of a wheel, so to one’s self are fastened all beings, all the gods, all the worlds, all the breaths, and all bodies. 
In one story, even the warrior-god Indra laid down his weapons to become a renouncer. We read:
Brahman had won a victory for the gods [The gods], however, exulting in that victory of Brahman, imagined it to have been their own, thinking: “Ours, indeed, is this victory! Ours the glory!” Brahman, therefore, understood their pride and appeared before them, but they did not know what Brahman was.
“What sort of specter can this thing be?” they asked. And they said to Agni: “O thou Almost Omniscient One, find out what this thing is.” “Yes,” said he, and he ran to it. Brahman asked: “Who are you?” “I am the famous Agni, the Almost Omniscient One,” he said. Brahman asked: “What power in you warrants such fame?” And the god replied: “I can burn things up, whatever there is on earth.” Brahman put a straw down before him. “Burn that!” Agni came at it with all his force. He was unable to burn it. He returned to the gods. “I have not been able to learn,” said he, “what that specter is.”
The gods then said to Vayu: “O thou Wind, find out what this specter is.” “Yes,” said he, and he ran to it. Brahman asked: “Who are you?” “I am the famous Vayu, the One Who Moves Through the Sky,” he said. Brahman asked: “What power in you warrants such fame?” and the god replied: “I can carry things away, whatever there is on earth.” Brahman put a straw down before him. “Carry that away!” said Brahman. Vayu came at it. With all his force he was unable to carry it away. He returned to the gods. “I have not been able to learn,” said he, “what that specter is.”
Then, the gods said to Indra: “O thou Worshipful One, find out what that specter is.” “Yes,” he answered and he ran toward it, but it vanished before him. In that very place he came upon a woman of great beauty, Uma Haimavati, the Daughter of the Snowy Mountain. He asked her: “What was that specter?” She answered: “Brahman. Through the victory of that Brahman, you attained the glory in which you take such pride.” From this, Indra learned of Brahman.” 
Another dramatic consequence of this new reasoning was the devaluation of ritual. Why sacrifice to the gods when they are subject to the same reality? To worship anything other than atman had become foolish. Instead of burning a sacrificial fire for the gods, the goal became to ignite the fire within the self.
In the Upanishads, we also find the first detailed account of the doctrine of the transmigration of souls, commonly known as reincarnation. It was believed that the soul was reborn after death, either in the form of another human being, or as an animal, god, demon, or even an inanimate object. Yajnavalkya compared this succession of lives to the movement of a caterpillar from one blade of grass to another:
It is like this. As a caterpillar, when it comes to the tip of a blade of grass, reaches out to a new foothold and draws itself onto it, so the self (atman), after it has knocked down this body and rendered it unconscious, reaches out to a new foothold and draws itself onto it. 
In what form a person reappeared was believed to depend on karma (literally meaning “action”), which functioned as a system of universal justice. Good deeds result in good karma, which counts toward a favorable rebirth. Similarly, bad deeds result in bad karma, which leads to a lower rebirth. Karma thus steers the soul automatically to the next rebirth. While, to a Western mind, the idea of another life might seem pleasant (especially if one can become a god), the renouncers saw themselves as trapped in an endless cycle of death and rebirth, which they called samsara (meaning “wandering”). The souls were believed to forever aimlessly wander from one body to the next in a world filled with suffering.
Even the gods were believed to be subject to karma and were, therefore, stuck in the same cycle. In one story, Indra ordered a divine architect to build him a palace to celebrate his victory over Vritra. However, the architect soon became tired of Indra’s impossible demands. He went to the god Brahma and asked for help to cool down his ambitions. Brahma visited Indra in the shape of a boy and began to cry. Indra asked what was wrong, and the boy pointed to a line of ants. He explained that these ants had all been former Indras, not once, but a million times. Realizing this would also be his fate, Indra suddenly became aware of the ridiculousness of his vanity.
Some renouncers began to reject both good and bad karma. Instead of focusing on a more favorable rebirth, they wanted to escape the cycle altogether. This release from samsara is called moksa and became the main goal of the spiritual quest. So, how can moksa be achieved? In the Upanishads, we read that simply doing good deeds is not enough. Treating others well and giving alms to the poor may ensure a favorable rebirth, but it will not allow someone to escape samsara. Instead, the only way out is to renounce everything that binds us to karma and to attain knowledge of the self. This, they claimed, was the only way for the self to “pass across sorrow.” The philosopher-king Jaivali (c. 7th century BC) explained this concept to a student:
Those, who, dwelling in the forest, venerate thus: “austerity is faith” [or in another version: “venerate truth as faith”], pass into the flame of the cremation fire, and from the flame into the day; from the day into the fortnight of the waxing moon; from that into the six months of the sun trending north; thence, into the year and from the year into the sun; from the sun into the moon; and from the moon into the lightning, where there is a non-human Person, who leads them beyond, to Brahma. This is the way to the gods.
But those who in the village reverence sacrifice, merit, and almsgiving [or in the other version “and by performing austerities”], pass into the smoke of the sacrificial fire and from the smoke into the night; from the night, into the latter fortnight of the month; from that into the six months of the sun trending south-which do not culminate the year; from those months, into the world of the fathers; from the world of the fathers, into space; from space into the moon. That is King Soma. That is the food of the gods. That is what the gods eat.
And so remaining in that place just as long as the merit of their good works lasts, they return along the course by which they came. They move into space, and from space, into wind. Having been wind, they become smoke, and after being smoke, they become mist. After mist, they become cloud. After being cloud, they fall as rain, and are born as rice or barley, herbs, trees, sesame or beans, from which condition it is difficult indeed to emerge. For only if someone or other eats him as food and then emits him as semen, can anyone so caught develop further.
For those who have been of pleasant conduct here on earth the prospect then is, however, that they will enter a pleasant womb, either of a Brahmin, Kshatriya or Vaishya. But for those who are of stinking conduct here the prospect is, indeed, that they will enter a stinking womb, either of a dog, a pig, or an outcast. 
Meditation is only mentioned in later post-Buddhist Upanishads. In the Svetasvatara Upanishad, for instance, meditation is defined by a focus on the breath and a slowing down of inhalations and exhalations to “restrain the mind.” We read:
The wise man should hold his body steady, with the three upper parts [chest, head, and neck] erect, turn his senses, with the help of the mind, toward the heart, and by means of the raft of brahman cross the fearful torrents of the world. Having repressed his breathings here in the body, and having his movements checked, he should breathe through his nostrils with diminished breath. Then let him undistractedly restrain his mind, as a charioteer restrains his vicious horses. 
Another clue about the exceptional control the early yogis had over body and mind comes from biographies of Alexander the Great (356–323 BC), who invaded India in the fourth century BC. His men found fifteen naked monks sitting motionless on sunbaked rocks that were so hot that none of the Macedonian soldiers could step on them without shoes. When the soldier in charge asked the monks for their wisdom, they responded that no one wearing the elaborate clothing of the Macedonians could be taught philosophy. They should first be naked and learn to sit peacefully on a broiling rock. One monk was willing to meet Alexander. He asked for a large pyre to be built, mounted the pyre, assumed the cross-legged yoga posture, and set himself on fire. As the flames wrapped around him, he continued to sit motionless while his body turned to ashes.
Fig. 223 – Yogis under a banyan tree (1630) (British Museum)
A much more mature description of meditation is found in the Yoga Sutra, written by Patanjali, likely in the first centuries AD. The term yoga is defined in the first line:
Yoga is the intentional stopping of the spontaneous activity of the mind-stuff. 
In its natural state, as the text claims, the mind is perfectly calm and quiet, and the yogi is fully enlightened. The problem is, however, that we have accustomed our mind to addictively jump from one thought to the next. The average person cannot even focus on a single thought or object for more than a few seconds. Instead of identifying with atman, we have become fully consumed by our thoughts. We read:
The identity of the seer becomes entangled with thought patterns.
The text then describes in detail how this entanglement has come about. The text first mentions ignorance. A person might regard that which is transient as eternal, he might mistake the impure for the pure, he might think that something that brings misery will bring happiness, and he might take that which is not-atman to be atman. Another cause is identification with the ego (asmita), which causes a person to take the intellect (buddhi) as pure consciousness. Another problem is attachment and aversion, caused by thoughts of pleasure and misery. Finally, the text names resistance to loss and love for continuation as problems.
To solve these problems, the text advises one to “allow the gross and subtle fluctuations of the mind to recede back into the field from which they arose” by practicing non-attachment (vairagya). Eventually the mind will finally be at rest, “losing even the desire for objects seen or described in tradition or in scriptures.” To get here, Patanjali identifies a number of steps. He starts with self-restraint, which includes “non-violence (ahimsa), truthfulness, […] walking in awareness of the highest reality and non-possessiveness or non-grasping with the senses.” The second step focuses on self-training, which includes “cleanliness and purity of body and mind, an attitude of contentment, training of the senses, […] and an attitude of letting go into one’s source.”
The yogi then learns to sit for long periods in the traditional yoga posture (asana), with legs crossed and a straight back. We read:
The posture (asana) for yoga meditation should be steady, stable, and motionless, as well as comfortable. […] The means of perfecting the posture is that of relaxing or loosening of effort, and allowing attention to merge with endlessness or the infinite.
The fourth step is breath control (pranayama). We read:
Once that perfected posture has been achieved, the slowing and regulating of the inhalation and exhalation is called breath control (pranayama), which leads to the absence of the awareness of both. […] Calm the mind by regulating the breath, particularly attending to exhalation and the natural stilling of breath that comes from such practice.
With the fifth step comes the withdrawal of the senses:
When the senses cease to be engaged with the corresponding objects in their mental realm, and assimilate or turn back into the mind-field from which they arose, this is called the withdrawal of the senses.
Then comes concentration (dharana), which the text defines as “the process of fixing the attention of the mind onto one object or place.” The stage of meditation (dhyana) is reached when the yogi can sustain “the uninterrupted continuation of that one point of focus.” When the ability to focus is finally perfected, the yogi reaches perfect concentration (samadhi).
Modern MRI research has, indeed, shown that experienced meditators can use the thinking part of the brain (the prefrontal cortex) to inhibit the endless stream of thoughts (called the default system). As a result, these meditators can focus on a single object without getting distracted. The most experienced meditators (> 12,000 hours) did something even more remarkable. They only needed their prefrontal cortex to focus in on their target, but then they were able to sustain their focus without any effort. 
By practicing concentration, the Yoga Sutra claims, the mind will eventually see the world without distortion:
The mind becomes like a transparent crystal, and thus can easily take on the qualities of whatever object observed, whether that object be the observer, the means of observing, or an object observed. When the mind is purified, then the mind appears to be devoid of its own nature and only the object on which it is contemplating appears to shine forward.
Finally, the text mentions an additional step, which entails letting go of even the focal point of the meditation without losing perfect concentration. In this state of mind, we see the world as it truly is.
The Bhagavad Gita (“The Song of God”) is another defining text of Hinduism. The text was probably written around the second century BC and describes a scene from the great Indian epic called the Mahabharata. This epic describes a horrific war between two groups of cousins, the Kauravas and the Pandavas, who fought over a regional kingdom. The Bhagavad Gita describes a scene on the eve of this battle, when the armies were already stationed in front of each other. On the side of the Pandavas, a man named Arjuna threw down his bow in despair as he did not want to kill his cousins in battle. But then Prince Krishna stepped in, who was not only Arjuna’s chariot driver and cousin but also a god in human form. Krishna convinced Arjuna to fight. He reasoned that it was Arjuna’s duty to fight since he was a member of the Kshatriya caste, making fighting his dharma (his duty). He also explained that since our atman is equal to Brahman, there is, in reality, nothing troubling about death. Arjuna should act according to his duty and use meditation to detach himself from the consequences of his actions.
Krishna also recommended bhakti yoga, which meant cultivating total devotion and love for the divine, thereby quenching the desire for anything of this world. Krishna showed how this path was open to all human beings, regardless of caste. Any person could act out of love for god, and even the humblest offering would be received equally by the gods as long as it was given from a place of love.
After this explanation, Krishna revealed to Arjuna his divine cosmic nature:
Arjuna saw in that universal form unlimited mouths and unlimited eyes. It was all wondrous. The form was decorated with divine, dazzling ornaments and arrayed in many garbs. He was garlanded gloriously, and there were many scents smeared over his body. All was magnificent, all-expanding, unlimited. This was seen by Arjuna. […] At that time Arjuna could see in the universal form of the lord the unlimited expansions of the universe situated in one place although divided into many, many thousands.
Arjuna said: “My dear lord Krishna, I see assembled together in your body all the demigods and various other living entities. I see Brahma sitting on the lotus flower, as well as lord Shiva and many sages and divine serpents. You are the origin without beginning, middle or end. You have numberless arms, and the sun and moon are among your great unlimited eyes. By your own radiance you are heating this entire universe. […] Although you are one, you are spread throughout the sky and the planets and all space between.” 
Then Arjuna witnessed Krishna’s doomsday form. He cried out:
I see your mouths with jagged tusks, and I see all of these warriors rushing blindly into your gaping mouths, like moths rushing to their death in a blazing fire. Some stick in the gaps between your teeth, and their heads are ground to powder. O Vishnu, I see you devouring all people in your flaming mouths and covering the universe with your immeasurable rays. Scorching the worlds, you are manifest.
When Arjuna asked Krishna who he was, he responded:
The blessed lord said: “Time I am, destroyer of the worlds, and I have come to engage all people. With the exception of you, all the soldiers here on both sides will be slain.’’
Arjuna could not comprehend what he saw. Being totally overwhelmed by the divine, he asked Krishna to return to his limited earthly form.
Fig. 224 – Arjuna and his charioteer Krishna (left) at the Mahabharata war (c. 1820) (Philadelphia Museum of Art)
The first signs of an interest in astronomy among the Hindus already appeared early on. In the Atharva Veda (1200-800 BC), the zodiac was divided into 27 (and later 28) segments called nakshastras, which allowed the Indians to trace the motion of the moon throughout the lunar month. In a text called Jyotisa, which based on its language must have been written down in the first centuries BC, we find that the moon passes through 1809 nakshastras in five years. From this we can calculate that the moon travels through each nakshastra in 1.0116 days. At a later time, the Indians also recognized two points in space called Rahu and Ketu, at which the path of the moon and the sun intersect. When both the moon and the sun arrive at this point, an eclipse occurs. 
In the 6th century BC, or perhaps somewhat earlier, the famous Takshila school was founded. In this school, students came to learn science, astrology, medicine, and other topics. A later renowned school at Nalanda was founded in 427 AD. At first, this school taught only Buddhism, but later expanded to other areas of knowledge, including astronomy, mathematics, and medicine. It is said that in the 7th century AD the school had 10,000 students and about 2,000 teachers, some coming from China, Tibet, Indonesia, Japan, Korea, Persia, and Turkey. At its height, the campus consisted of ten temples, hundreds of classrooms, meditation halls, a large library, and a scriptorium. Both schools are nowadays sometimes called universities, but it seems no research took place there and no degrees were awarded.
India also developed a great tradition of medicine, called ayurveda (meaning “knowledge of life”). Two of its foundational texts, written in poetic form, were written down between 400 and 200 BC. These works describe various drugs, including medicine for kidney stones, and various surgeries, such as dentistry, eye surgery, and even plastic surgery (for instance, repairing a damaged nose with skin from the neck). The theory behind ayurveda is based on the idea that the body, the mind, and the universe are spiritually interconnected. Disease occurs when these elements are out of balance. Ayurveda also promoted prevention, for which they recommended exercise and meditation.