A third ethical response to the speculations of Plato and Aristotle was led by Epicurus (341-270 B.C.). No ancient philosophy has been as generally and completely misunderstood as his Epicureanism. The common view is that Epicureans want a comfortable, sensual hedonism, combined with a crude atheism. This reputation arose largely because so many prostitutes came to join the Epicurean movement.

The actual situation was quite different: a small, exclusive group of refined quietists, of the highest moral character, with an extraordinary devotion to their founder, a most attractive theory and practice, and strong and loyal friendship. Epicurus himself was an amicable and cheerful man of extreme modestly ("Send me a cheese," he once wrote to a friend, "that I may fare sumptuously"). But his movement was extremely unpopular in the ancient world, since its teachings countered the Stoics, Platonists, and Aristotelians. It's tough to swim upstream, especially when the big fish are moving the other way.

The Epicurean aim of life was simple: happiness as the absence of pain and the presence of tranquility. They denied the Stoic approach to fatalism, since it was disturbing to the mind and prevented tranquility. They rejected Cynicism for its similar denials of tranquil pleasures. And they had little interest in the speculations of Plato and Aristotle, since they could bring few pleasures to life.

Epicurus developed an epistemology, theology, and psychology. His theory of learning was quite creative: the physical world is made of atoms (agreeing with the Atomists); the atoms on the outer layer of things are given off as the "images" of their material subjects. These "images" float through the air until they contact a perceiving subject. Then they make an actual physical impression on the sense-organ, penetrating through the pore directly to the mind and producing mind-pictures. Since images are sometimes mixed (as with a centaur, combining the images of a man and a horse), concepts come from the images as they are creatively assimilated and understood. Not a bad guess, and closer to modern theory than any other in ancient Greek speculation.

His theology was less creative. The gods must exist, he said, or else we could not have their image in our minds. Yet they form no part of the physical universe, living in perfect tranquility and representing the ideal of human life. Epicurean religion was simply the contemplation of the divine life.

And his psychology was similar to his epistemology. The soul is composed of atoms, themselves material in nature. Soul-atoms are diffused all over the body, causing every sensation we feel. The directing, rational part of the soul is located in the breast. And the soul is mortal, dissolving into its material elements when the body dies. Death ends all consciousness. And so we should have no fear of death and the beyond, leaving us free for present happiness.