 Plato’s Timaeus elaborates an account of the world wherein the four different basic kinds of body—earth, air, fire, and water—are regular solids composed from plane figures: isosceles and scalene right-angled triangles. Because the same triangles can form into different regular solids, the theory thus explains how some of the elements can transform into one another, as was widely believed. In this theory, it is the elemental triangles composing the solids that are regarded as indivisible, not the solids themselves. When Aristotle discusses the hypothesis that the natural world is composed of indivisibles, the two views he considers are those of Plato and Democritus. Aristotle criticizes both Plato and fourth-century Pythagoreans for constructing natural bodies possessing weight from indivisible mathematical abstractions, whether plane surfaces or numbers. It has been suggested that Plato accepted time atoms, i.e., indivisible minima in time, but this is controversial.