 Ancient Greek atomists developed a systematic and comprehensive natural philosophy accounting for the origins of everything from the interaction of indivisible bodies, as these atoms—which have only a few intrinsic properties like size and shape—strike against one another, rebound and interlock in an infinite void. In both its Democritean and its Epicurean versions, Greek atomism eschewed teleological explanation and denied divine intervention or design, regarding every composite of atoms as produced purely by material interactions of bodies, and accounting for the perceived properties of macroscopic bodies as produced by these same atomic interactions. Ancient Greek atomists formulated views on ethics, theology, political philosophy and epistemology consistent with this physical system. This powerful and consistent materialism was regarded by Aristotle as a chief competitor to teleological natural philosophy; following his criticisms, the theory was reformulated by Epicurus and had a second life as the philosophy of a school devoted to the pursuit of tranquillity and a communal life of simple pleasures.