Epicureanism is a system of philosophy based upon the teachings of the ancient Greek philosopher Epicurus, founded around 307 BC. Epicurus was an atomic materialist. His materialism led him to a general attack on superstition and divine intervention. …Epicurus believed that what he called “pleasure” (ἡδονή) was the greatest good, but that the way to attain such pleasure was to live modestly, to gain knowledge of the workings of the world, and to limit one’s desires. This would lead one to attain a state of tranquility (ataraxia) and freedom from fear as well as an absence of bodily pain (aponia). The combination of these two states constitutes happiness in its highest form. Although Epicureanism is a form of hedonism insofar as it declares pleasure to be its sole intrinsic goal, the concept that the absence of pain and fear constitutes the greatest pleasure, and its advocacy of a simple life, make it very different from “hedonism” as colloquially understood.
Epicurus emphasized friendship as an important ingredient of happiness, and the school [in Athens called “The Garden”] seems to have been a moderately ascetic community which rejected the political limelight of Athenian philosophy. They were fairly cosmopolitan by Athenian standards, including women and slaves. Some members were also vegetarians as, from slender evidence, Epicurus did not eat meat, although no prohibition against eating meat was made.
In Dante Alighieri‘s Divine Comedy, the Epicureans are depicted as heretics suffering in the sixth circle of hell. In fact, Epicurus appears to represent the ultimate heresy. (taken from the Wikipedia entry on Epicureanism)