, refined it. The Persians made fire a purer and lighter spirit,
so that the stars would need no support. But everywhere the blue vault
hemmed in the world and the ideas of men. It was so close, some said,
that the birds could reach it. At last the genius of Greece brooded over
the whole chaos of cosmical speculations.

The native tradition of Greece was a little more helpful than the
Babylonian teaching. First was chaos; then the heavier matter sank to
the bottom, forming the disk of the earth, with the ocean poured round
it, and the less coarse matter floated as an atmosphere above it,
and the still finer matter formed an "aether" above the atmosphere.
A remarkably good guess, in its very broad outline; but the solid
firmament still arched the earth, and the stars were little undying
fires in the vault. The earth itself was small and flat. It stretched
(on the modern map) from about Gibraltar to the Caspian, and from
Central Germany--where the entrance to the lower world was located--to
the Atlas mountains. But all the varied and conflicting culture of the
older empires was now passing into Greece, lighting up in succession the
civilisations of Asia Minor, the Greek islands, and then Athens and its
sister states. Men began to think.

The first genius to have a glimpse of the truth seems to have been
the grave and mystical Pythagorus (born about 582 B.C.). He taught his
little school that the earth was a globe, not a disk, and that it turned
on its axis in twenty-four hours. The earth and the other planets
were revolving round the central fire of the system; but the sun was a
reflection of this central fire, not the fire itself. Even Pythagoras,
moreover, made the heavens a solid sphere revolving, with its stars,
round the central fire; and the truth he discovered was mingled with so
much mysticism, and confined to so small and retired a school, that it
was quickly lost again. In the next generation Anaxagoras taught that
the sun was a vast globe of white-hot iron, and that the stars were
material bodies made white-hot by friction with the ether. A generation
later the famous Democritus came nearer than any to the truth. The
universe was composed of an infinite number of indestructible particles,
called "atoms," which had gradually settled from a state of chaotic
confusion to their present orderly arrangement in large masses. The sun
was a body of enormous size, and the points of light in the Milky Way
were similar su