Epicurus developed an unsparingly materialistic metaphysics, empiricist epistemology, and hedonistic ethics.
Epicurus taught that the basic constituents of the world are atoms, uncuttable bits of matter, flying through empty space, and he tried to explain all natural phenomena in atomic terms. Epicurus rejected the existence of Platonic forms and an immaterial soul, and he said that the gods have no influence on our lives.
Epicurus also thought skepticism was untenable, and that we could gain knowledge of the world relying upon the senses. He taught that the point of all one’s actions was to attain pleasure (conceived of as tranquility) for oneself, and that this could be done by limiting one’s desires and by banishing the fear of the gods and of death.
Epicurus’ gospel of freedom from fear proved to be quite popular, and communities of Epicureans flourished for centuries after his death.
Epicurus’ ethics is a form of egoistic hedonism; i.e., he says that the only thing that is intrinsically valuable is one’s own pleasure; anything else that has value is valuable merely as a means to securing pleasure for oneself. However, Epicurus has a sophisticated and idiosyncratic view of the nature of pleasure, which leads him to recommend a virtuous, moderately ascetic life as the best means to securing pleasure. This contrasts Epicurus strongly with the Cyrenaics, a group of ancient hedonists who better fit the stereotype of hedonists as recommending a policy of “eat, drink, and be merry.”