Furthermore, it is said that Numa built the temple of Vesta, where the perpetual fire was kept, of a circular form, not in imitation of the shape of the earth, believing Vesta to be the earth, but of the entire universe, at the centre of which the Pythagoreans place the element of fire, and call it Vesta and Unit. And they hold that the earth is neither motionless nor situated in the centre of surrounding space, but that it revolves in a circle about the central fire, not being one of the most important, nor even one of the primary elements of the universe. This is the conception, we are told, which Plato also, in his old age, had of the earth, namely that it is established in a secondary space, and that the central and sovereign space is reserved for some other and nobler body.