In Egypt in the first centuries AD, chemists developed the curious goal of creating a stone that could turn any metal into gold.
At the time, this did not seem to farfetched, since according to Aristotle, all matter was made from exactly the same substance (called prime matter), but infused with different amounts of hot-, cold-, wet- and dryness. Changing one metal into the other should therefore be a matter of changing these superficial qualities.
The Ouroboros serpent became associated with Aristotle's prime matter, the simple and coarse substance from which any metal could be made and with which one metal could be turned into another. It is in this light that we must understand the words "The All is One", written inside the Ouroboros in one of the oldest alchemical texts found.
"The Great World History Book"