 Epicurus seems to have learned of atomist doctrine through Democritus’ follower Nausiphanes. Because Epicurus made some significant changes in atomist theory, it is often thought that his reformulation of the physical theory is an attempt to respond to Aristotle’s criticisms of Democritus. Even more significant, however, is the increasing centrality of ethical concerns to Epicurus’ atomism, and the importance of the view that belief in an atomist physical theory helps us live better lives.