were obliged to imagine a system of tunnels that gradually became enlarged to the intervals between the pillars."
The Hindoos held the earth to be hemispherical, and to be supported like a boat turned upside down upon the heads of four elephants, which stood on the back of an immense tortoise. It is usually said that the tortoise rested on nothing, but the Hindoos maintained that it floated on the surface of the universal ocean. The learned Hindoos, however, say that these animals were merely symbolical, the four elephants meaning the four directions of the compass, and the tortoise meaning eternity. The idea that the earth floated long prevailed, and was adopted by Thales, the early Greek philosopher, and by Seneca several centuries later.
Anaximander, a philosopher of the sixth century before Christ, represented the earth as a cylinder, the upper face alone of which is inhabited. He computed its proportions, and stated that it is one-third as high as its diameter; and he declared that it floats freely in
the centre of the celestial vault, because there is no reason why it should move to one side rather than to the other. Leucippus, Democritus, Heraclitus, and Anaxagoras, all agreed with him, and Anaximenes added the opinion, in consequence of the importance of air in the world, that the earth is supported on compressed air.
Plato was a mathematician, and excogitated the universe out of the depths of his geometrical consciousness. In explaining how things came about, he said that matter in itself had no form or properties, but God in the beginning invested it with a sort of triangular constitution. Afterward, taking a certain number of these primitive triangles, be composed the four primary elements. Fire, the most subtile, is made up of the smallest number of triangles, and has the figure of a pyramid. Water-particles are solids of twenty faces, while the earth-element is cubical or bounded by right-angled triangles. The cube with its six equal faces appeared to Plato to be the most perfect of solids, and therefore most suitable for the earth, which was to stand in the centre of the universe.