Plotinos: Complete Works, v. 1 In Chronological Order,...

Those sages who (like Leucippus, Democritus and Epicurus) assumed material principles such as the atoms, and who explain everything by their motion, their shock and combinations, pretend that everything existent and occurring is caused by the agency of these atoms, their "actions and reactions." This includes, according to them, our appetites and dispositions. The necessity residing in the nature of these principles, and in their effects, is therefore, by these sages, extended to everything that exists. As to the (Ionic Hylicists), who assume other physical (ultimate) principles, referring everything to them, they thus also subject all beings to necessity.