  To take one example, Gassendi assumes material objects must have some substratum composed of basic and indivisible elements (‘principles’), and proposes that atoms, as the best candidates for the role of substrata, are the material principles in question. To arrive at this first assumption, he follows Epicurus and Lucretius in adopting the Parmenidean dicta that nothing comes from nothing and (conversely) that all matter must come from something. He further embraces the ancient view that those dicta entail a common substratum for all matter, as the composition and resolution of material things always yield matter. To establish that atoms are the best candidates for serving as this common substratum, he reasons that whatever would serve as matter's substratum cannot pass from existence. Moreover, elements of such substratum would be incapable of passing from existence only if they were indivisible and thus had no void—that is, were solid. Yet this common substratum cannot be featureless, formless primary matter, as the Aristotelians propose. It should have some identifiable and unchanging features because such features are ineliminable from matter. He concludes that all material objects must be composed of elemental particles sharing the features essential to matter—and the particles with those features just are atoms.