agorean doctrines. It
was not strange, then, that the man who was finally to carry these new
opinions to their logical conclusion should hail from Samos.

But what was the support which observation could give to this new,
strange conception that the heavenly bodies do not in reality move as
they seem to move, but that their apparent motion is due to the actual
revolution of the earth? It is extremely difficult for any one nowadays
to put himself in a mental position to answer this question. We are so
accustomed to conceive the solar system as we know it to be, that we
are wont to forget how very different it is from what it seems. Yet one
needs but to glance up at the sky, and then to glance about one at the
solid earth, to grant, on a moment's reflection, that the geocentric
idea is of all others the most natural; and that to conceive the sun
as the actual Centre of the solar system is an idea which must look for
support to some other evidence than that which ordinary observation can
give. Such was the view of most of the ancient philosophers, and such
continued to be the opinion of the majority of mankind long after the
time of Copernicus. We must not forget that even so great an observing
astronomer as Tycho Brahe, so late as the seventeenth century, declined
to accept the heliocentric theory, though admitting that all the planets
except the earth revolve about the sun. We shall see that before the
Alexandrian school lost its influence a geocentric scheme had been
evolved which fully explained all the apparent motions of the heavenly
bodies. All this, then, makes us but wonder the more that the genius of
an Aristarchus could give precedence to scientific induction as against
the seemingly clear evidence of the senses.

What, then, was the line of scientific induction that led Aristarchus to
this wonderful goal? Fortunately, we are able to answer that query, at
least in part. Aristarchus gained his evidence through some wonderful
measurements. First, he measured the disks of the sun and the moon.
This, of course, could in itself give him no clew to the distance of
these bodies, and therefore no clew as to their relative size; but in
attempting to obtain such a clew he hit upon a wonderful yet altogether
simple experiment. It occurred to him that when the moon is precisely
dichotomized--that is to say, precisely at the half-the line of vision
from the earth to the moon must be precisely at right angles with the
line o