ns at a tremendous distance from the earth. Our universe,
moreover, was only one of an infinite number of universes, and an
eternal cycle of destruction and re-formation was running through these
myriads of worlds.

By sheer speculation Greece was well on the way of discovery. Then the
mists of philosophy fell between the mind of Greece and nature, and
the notions of Democritus were rejected with disdain; and then, very
speedily, the decay of the brilliant nation put an end to its feverish
search for truth. Greek culture passed to Alexandria, where it met the
remains of the culture of Egypt, Babylonia, and Persia, and one more
remarkable effort was made to penetrate the outlying universe before the
night of the Middle Ages fell on the old world.

Astronomy was ardently studied at Alexandria, and was fortunately
combined with an assiduous study of mathematics. Aristarchus (about
320-250 B.C.) calculated that the sun was 84,000,000 miles away; a vast
expansion of the solar system and, for the time, a remarkable approach
to the real figure (92,000,000) Eratosthenes (276-196 B.C.) made an
extremely good calculation of the size of the earth, though he held it
to be the centre of a small universe. He concluded that it was a globe
measuring 27,000 (instead of 23,700) miles in circumference. Posidonius
(135-51 B.C.) came even nearer with a calculation that the circumference
was between 25,000 and 19,000 miles; and he made a fairly correct
estimate of the diameter, and therefore distance, of the sun. Hipparchus
(190-120 B.C.) made an extremely good calculation of the distance of the
moon.

By the brilliant work of the Alexandrian astronomers the old world
seemed to be approaching the discovery of the universe. Men were
beginning to think in millions, to gaze boldly into deep abysses of
space, to talk of vast fiery globes that made the earth insignificant
But the splendid energy gradually failed, and the long line was closed
by Ptolemaeus, who once more put the earth in the centre of the system,
and so imposed what is called the Ptolemaic system on Europe. The keen
school-life of Alexandria still ran on, and there might have been a
return to the saner early doctrines, but at last Alexandrian culture was
extinguished in the blood of the aged Hypatia, and the night fell.
Rome had had no genius for science; though Lucretius gave an immortal
expression to the views of Democritus and Epicurus, and such writers
as Cicero and Pliny d