One striking oddity about Democritus and Epicurus is that, even though Epicurus' theory of perception is largely the same as that of Democritus, Democritus and his followers draw skeptical conclusions from this theory of perception, whereas Epicurus declares that all perceptions are true or real. I believe that the dispute between Democritus and Epicurus stems from a question over what sort of ontological status should be assigned to sensible qualities. In this paper, I address three questions: 1) Why were Democritus (...) and his followers skeptical? 2) How did Epicurus modify Democritus' metaphysics in order to avoid these skeptical conclusions? and 3) How successful was he? -/- 1) I argue that Democritus allows only the intrinsic properties of atoms into his ontology, and then runs into skeptical difficulties because of the relativity of perception. 2) I propose that Epicurus modifies Democritus' ontology by allowing dispositional and relational properties as real properties of bodies. Sensible qualities are conceptualized as dispositional properties of bodies to cause certain experiences in percipients. 3) I argue that Epicurus does not run into the same problems as Democritus. Finally, I consider how my interpretation of Epicurus' ontology helps to make sense of his claim that all perceptions are alethes--'true' or 'real.'. (shrink)