There are many good reasons for seeing Aristotelian hylemorphism and atomism as diametrically opposed theories of matter. Aristotle himself had forcefully combatted the physical model of Leucippus and Democritus, whose ontology consisted of indivisible material bodies moving in an immaterial void, presenting his own model as an alternative. This alternative excluded both indivisibles and the void and postulated instead a plenist world made up of substances all of which were infinitely divisible continua composed of universal matter and specific substantial forms. (...) Unlike elementary atoms, Aristotle’s elementary substances could transmute into one another: water, when evaporating, was said to turn into air. (shrink)