Aristotle
Sonse, CC BY 2.0 , via Wikimedia Commons

A number of interesting thinkers lived in Athens in the sixth and fifth centuries BC. These people began asking big questions that still puzzle and intrigue intelligent people today. Their thoughts may seem strange and abstract if you try to sum them up, but they were important steps in thinking about reality systematically.

A group called the Milesians included Thales, who thought everything was made of water; Anaximander, who thought a substance called apeiron was the source of everything; and Anaximenes, who thought everything was made of air. Anaxagoras thought matter was an infinitely divisible mixture of elements, as opposed to Democritus, who believed reality consisted of little indivisible particles called "atoms." Heraclitus believed there was no such thing as things, and change was the only constant; in contrast, Parmenides of Elea, believed change was impossible. His student, Zeno, tried to prove him right mathematically using arguments of infinite divisibility.

The three most important philosophers, however, were Socrates, Plato, and Aristotle. Most of Plato's writings are highly refined literature featuring dialogues between Socrates and his interlocutors. His most significant ideas are the Theory of Forms and the Allegory of the Cave. Alfred North Whitehead said "all of European philosophy is a series of footnotes to Plato."

Aristotle was a student of Plato, and possibly the most important thinker of all time. Although not as much fun to read as Plato, because his surviving works are basically lecture notes, rather than fully completed dialogues, he laid the foundations for metaphysics, rhetoric, poetry, ethics, and empirical science. Although many of his scientific theories have been disproven, his thought in other areas (particularly in ethics and metaphysics) has not and remains influential. Aristotle served as a tutor to Alexander the Great, thus spreading his ideas about virtue ethics, the four causes, and hylemorphic dualism around the known world.

Both Plato and Aristotle wrote somewhat extensively about music. In The Republic, Book III, Plato discusses different types of harmonies and instruments and their effects on people. Although the reasoning is not entirely clear, the Ionian and Lydian modes are dismissed as "soft and convivial," resulting in "drunkenness and indolence." The Dorian and Phrygian modes, on the other hand, are mentioned as "of use for warlike men." Plato also says that a perfect society would ban all instruments other than lyres and harps, although shepherds would still be permitted the use of pipes.

This discussion may seem strange to a modern reader, but it is interesting to note that both Plato and Confucius, though writing in different societies on opposite sides of the world, agree that music is above else a tool for the development of character. Both believed music had objective effects on the soul that needed to be understood and properly managed. Plato's view can be summed up in this quote:

Musical training is a more potent instrument than any other, because rhythm and harmony find their way into the inward places of the soul, on which they mightily fasten, imparting grace, and making the soul of him who is rightly educated graceful, or of him who is ill-educated ungraceful: and also because he who has received this true education of the inner being will most shrewdly perceive omissions or faults in art and nature, and with a true taste, while he praises and rejoices over and receives into his soul the good, and becomes noble and good, he will justify blame and hate the bad, now in the days of his youth, even before he will recognize and salute the friend with whom his education has made him long familiar."