THE greek philosophers
Let's first get an overview of the era:
Starting in the 7th century BC, the Greek philosophers began to believe in the capacity of reason to understand the universe.
Instead of interpretating events in the world as the will of the gods, they began to look for naturalistic explanations. As a result, Aristotle named these philosophers physiologoi
(physicists), in contrast to the earlier theologoi
With this idea, they developed a rudimentary form of science.
The four elements
For example, Empedocles believed that everything in the world was made from the four elements—fire, water, earth and, air.
Leucippus and Democritus famously concluded that everything in the world was made out of atoms.
Pythagoras discovered that the sounds of different blacksmith hammers sounded well together, when their masses differed according to fixed mathematical ratios. This led him to conclude that mathematics must be the source of all things. He wrote:
"World is Number."
Now let's see this period through the eyes of an individual:
A early physiologoi who went especially far in his materialistic worldview was Anaxagoras, who lived in the 5th century BC.
Before his time, it was assumed that earthquakes were caused by restless gods, but Anaxagoras instead suggested they were caused by air escaping from cavities below the earth.
He also famously denied that the sun was a god and instead described it as a "glowing stone."