  The broadest atomist claims Gassendi makes are rooted in his background metaphysics and rejection of the infinite divisibility of matter. He grounds the finer points of his atomism—regarding the qualities of atoms and their aggregates—on observations, experiment, and interpretations of the same, as well as his assessments of alternative perspectives on matter theory. Following the Epicurean model (with debts to Lucretius, Democritus, and others still), he starts with a basic ontology of matter and void, and develops a thoroughgoing account of the physical world rooted in a picture of the inherent features of atoms. The general range of phenomena and entities for which Gassendi offers atomist accounts owes much to the ancients. Many of the particular explananda do not, though, and a significant number of his explanatory arguments are his own, at least in part.