The Story of Evolution | Page 6

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 did great service to a later age in preserving
fragments of the older discoveries. The curtains were once more drawn
about the earth. The glimpses which adventurous Greeks had obtained
of the great outlying universe were forgotten for a thousand years. The
earth became again the little platform in the centre of a little world, on
which men and women played their little parts, preening themselves on
their superiority to their pagan ancestors.
I do not propose to tell the familiar story of the revival at any length.
As far as the present subject is concerned, it was literally a Renascence,
or re-birth, of Greek ideas. Constantinople having been taken by the
Turks (1453), hundreds of Greek scholars, with their old literature,
sought refuge in Europe, and the vigorous brain of the young nations
brooded over the ancient speculations, just as the vigorous young brain
of Greece had done two thousand years before. Copernicus (1473-1543)
acknowledges that he found the secret of the movements of the
heavenly bodies in the speculations of the old Greek thinkers. Galilei

(1564-1642) enlarged the Copernican system with the aid of the
telescope; and the telescope was an outcome of the new study of optics
which had been inspired in Roger Bacon and other medieval scholars
by the optical works, directly founded on the Greek, of the Spanish
Moors. Giordano Bruno still further enlarged the system; he pictured
the universe boldly as an infinite ocean of liquid ether, in which the
stars, with retinues of inhabited planets, floated majestically. Bruno
was burned at the stake (1600); but the curtains that had so long been
drawn about the earth were now torn aside for ever, and men looked
inquiringly into the unfathomable depths beyond. Descartes
(1596-1650) revived the old Greek idea of a gradual evolution of the
heavens and the earth from a primitive chaos of particles, taught that
the stars stood out at unimaginable distances in the ocean of ether, and
imagined the ether as stirring in gigantic whirlpools, which bore cosmic
bodies in their orbits as the eddy in the river causes the cork to revolve.
These stimulating conjectures made a deep impression on the new age.
A series of great astronomers had meantime been patiently and
scientifically laying the foundations of our knowledge. Kepler
(1571-1630) formulated the laws of the movement of the planets;
Newton (1642-1727) crowned the earlier work with his discovery of
the real agency that sustains cosmic bodies in their relative positions.
The primitive notion of a material frame and the confining dome of the
ancients were abandoned. We know now that a framework of the most
massive steel would be too frail to hold together even the moon and the
earth. It would be rent by the strain. The action of gravitation is the
all-sustaining power. Once introduce that idea, and the great ocean of
ether might stretch illimitably on every side, and the vastest bodies
might be scattered over it and traverse it in stupendous paths. Thus it
came about that, as the little optic tube of Galilei slowly developed into
the giant telescope of Herschel, and then into the powerful refracting
telescopes of the United States of our time; as the new science of
photography provided observers with a new eye--a sensitive plate that
will register messages, which the human eye cannot detect, from far-off
regions; and as a new instrument, the spectroscope, endowed
astronomers with a power of perceiving fresh aspects of the inhabitants
of space, the horizon rolled backward, and the mind contemplated a
universe