rom observation to explanation. A new
and most important element was added to the science of astronomy.

Looking back from the latter-day stand-point, it would seem as if the
mind of the philosopher must have taken one other step: the mind that
had conceived sun, moon, stars, and earth to be of one substance might
naturally, we should think, have reached out to the further induction
that, since the moon is a sphere, the other cosmic bodies, including the
earth, must be spheres also. But generalizer as he was, Anaxagoras was
too rigidly scientific a thinker to make this assumption. The data
at his command did not, as he analyzed them, seem to point to this
conclusion. We have seen that Pythagoras probably, and Parmenides
surely, out there in Italy had conceived the idea of the earth's
rotundity, but the Pythagorean doctrines were not rapidly taken up in
the mother-country, and Parmenides, it must be recalled, was a strict
contemporary of Anaxagoras himself. It is no reproach, therefore, to the
Clazomenaean philosopher that he should have held to the old idea
that the earth is flat, or at most a convex disk--the latter being the
Babylonian conception which probably dominated that Milesian school to
which Anaxagoras harked back.

Anaxagoras may never have seen an eclipse of the moon, and even if he
had he might have reflected that, from certain directions, a disk may
throw precisely the same shadow as a sphere. Moreover, in reference
to the shadow cast by the earth, there was, so Anaxagoras believed,
an observation open to him nightly which, we may well suppose, was not
without influence in suggesting to his mind the probable shape of the
earth. The Milky Way, which doubtless had puzzled astronomers from the
beginnings of history and which was to continue to puzzle them for many
centuries after the day of Anaxagoras, was explained by the Clazomenaean
philosopher on a theory obviously suggested by the theory of the moon's
phases. Since the earth-like moon shines by reflected light at night,
and since the stars seem obviously brighter on dark nights, Anaxagoras
was but following up a perfectly logical induction when he propounded
the theory that the stars in the Milky Way seem more numerous and
brighter than those of any other part of the heavens, merely because
the Milky Way marks the shadow of the earth. Of course the inference was
wrong, so far as the shadow of the earth is concerned; yet it contained
a part truth, the f