The Pythagoreans had dealt with the sphere and regular solids, but the pyramid, prism, cone and cylinder were but little known until the Platonistss took them in hand. Eudoxus established their mensuration, proving the pyramid and cone to have one-third the content of a prism and cylinder on the same base and of the same height, and was probably the discoverer of a proof that the volumes of spheres are as the cubes of their radii.

**See also:** Archimedes, Demiurge, Johannes Kepler, planimetry, Plato, Plato's Timaeus

*...partly from the 1911 Encyclopaedia Britannica*