Anaxagorus was the first philosopher to visit Athens. Burnett described him as a Persian soldier from Klazomenai, a Greek city that had been conquered by the Persians. He was a teacher of Pericles, and a student of the school of Anaximenes. He was banished from Athens for saying that the sun was a red hot stone and that the moon was like earth. Anaxagorus began by trying to explain the world in a Milesian sense while respecting the conclusions of Parmenides. Empedokles had taught that everything in the world was made from four basic elements. Anaxagorus denied this possibility. He said that there was a little of everything in everything. Or else how could hair be made of what is not hair unless hair was part of it. All things are together, was the way he put it, and everything however small or great had an equal number of portions of the opposites. Matter is infinitely indivisible. No matter how small you may divide anything it still had the same number of opposites. However, everything gives the appearance of that which is most in it. Therefore air is that which has in it most cold, fire has in it most heat, and so on.


Of all of the followers of Parmenides by far the boldest was Leucippus who challenged the basic thesis of the masters philosophy, that what is not cannot be. When Pythagorus developed his theory of the one and the many, the many were separated by the void, or what is not. Parmenides rejected this idea. Leucippus revived it. Following the lead of Parmenides, Leucippus argued that what is must be one, but it is a plenum, he said, a plenum filled with an infinite number of bodies each of which meets all of the requirements of the one but are separated from all others by the void. These he called atoms. They were infinitely hard and indivisible, they came in a myriad shapes and sizes, and everything that exists is made up of them. This idea was further developed by Democritus and we will discuss him later because he was a contemporary of Plato, and like him a student of Socrates.

Undoubtedly the most important lesson to be learned in this study of the presocratic philosophers is that they raised more questions than they answered. 2600 years of philosophy and science have showed just how elusive the answers to these questions can be. But they set down a challenge to the western heritage that was to follow. The world is rational, it is understandable. It is through this understanding, based on that assumption, that has forced the west to reject magic and superstition as sources of knowledge. Next we shall look at the work of Plato, the first of the long line of philosophers who helped to develop answers to the questions posed by the presocratics.