"Epicureanism is a system of philosophy based upon the teachings of Epicurus, founded around 307 BC. Epicurus was an atomic materialist, following in the steps of Democritus. His materialism led him to a general attack on superstition and divine intervention. Following Aristippus—about whom very little is known—Epicurus believed that what he called "pleasure" is the greatest good, but the way to attain such pleasure is to live modestly and to gain knowledge of the workings of the world and the limits of one's desires. This led one to attain a state of tranquility (ataraxia) and freedom from fear, as well as absence of bodily pain (aponia). The combination of these two states is supposed to constitute happiness in its highest form. Although Epicureanism is a form of hedonism, insofar as it declares pleasure to be the sole intrinsic good, its conception of absence of pain as the greatest pleasure and its advocacy of a simple life make it different from "hedonism" as it is commonly understood.

Epicureanism was originally a challenge to Platonism, though later it became the main opponent of Stoicism. Epicurus and his followers shunned politics. After the death of Epicurus, his school was headed by Hermarchus; later many Epicurean societies flourished in the Late Hellenistic era and during the Roman era (such as those in Antiochia, Alexandria, Rhodes, and Ercolano). Its best-known Roman proponent was the poet Lucretius. By the end of the Roman Empire, being opposed by philosophies (mainly Neo-Platonism) that were now in the ascendance, Epicureanism had all but died out, and would be resurrected in the 17th century by the atomist Pierre Gassendi, who adapted it to the Christian doctrine.
Some writings by Epicurus have survived. Some scholars consider the epic poem On the Nature of Things by Lucretius to present in one unified work the core arguments and theories of Epicureanism. Many of the papyrus scrolls unearthed at the Villa of the Papyri at Herculaneum are Epicurean texts. At least some are thought to have belonged to the Epicurean Philodemus."
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- Epicurus & Epicurean Philosophy
- Internet Encyclopedia of Philosophy
- Stanford Encyclopedia of Philosophy