y the
dominant thinkers at the close of our epoch. In this regard, therefore,
a vast revolutionary work remains for the thinkers of a later period.
Moreover, such observations as the precession of the equinoxes and the
moon's evection are as yet unexplained, and measurements of the earth's
size, and of the sun's size and distance, are so crude and imperfect as
to be in one case only an approximation, and in the other an absurdly
inadequate suggestion. But with all these defects, the total achievement
of the Greek astronomers is stupendous. To have clearly grasped the idea
that the earth is round is in itself an achievement that marks off the
classical from the Oriental period as by a great gulf.

In the physical sciences we have seen at least the beginnings of great
things. Dynamics and hydrostatics may now, for the first time, claim a
place among the sciences. Geometry has been perfected and trigonometry
has made a sure beginning. The conception that there are four elementary
substances, earth, water, air, and fire, may not appear a secure
foundation for chemistry, yet it marks at least an attempt in the right
direction. Similarly, the conception that all matter is made up of
indivisible particles and that these have adjusted themselves and are
perhaps held in place by a whirling motion, while it is scarcely more
than a scientific dream, is, after all, a dream of marvellous insight.

In the field of biological science progress has not been so marked, yet
the elaborate garnering of facts regarding anatomy, physiology, and
the zoological sciences is at least a valuable preparation for the
generalizations of a later time.

If with a map before us we glance at the portion of the globe which was
known to the workers of the period now in question, bearing in mind
at the same time what we have learned as to the seat of labors of the
various great scientific thinkers from Thales to Galen, we cannot fail
to be struck with a rather startling fact, intimations of which have
been given from time to time--the fact, namely, that most of the great
Greek thinkers did not live in Greece itself. As our eye falls upon Asia
Minor and its outlying islands, we reflect that here were born such men
as Thales, Anaximander, Anaximenes, Heraclitus, Pythagoras, Anaxagoras,
Socrates, Aristarchus, Hipparchus, Eudoxus, Philolaus, and Galen.
From the northern shores of the aegean came Lucippus, Democritus,
and Aristotle. Italy, off to the west, is