The ancients discovered very early, that “the moon had no light of its
own, but shone with that which it reflected from the sun.” This, after
Thales, was the sentiment of Anaxagoras, and that of Empedocles, who
thence accounted not only for the mildness of its splendour, but the
imperceptibility of its heat, which our modern experiments confirm: for
with all the aid of burning glasses, we have never yet found it
practicable to obtain the least warmth from any combination of its rays.
With a telescope, we easily discern in the moon parts more elevated and
more bright than others, which are judged to be mountains; and means
have been found to measure their elevation. We discern also other parts,
lower and less bright, which must be vallies, lying between those
mountains. There are other parts, which reflecting less light, and
presenting one uniform smooth surface, may therefore be supposed large
pieces of water. As the moon, then, has its collections of water, its
atmosphere, its mountains, and its vallies; it is thence inferred, that
there may also be rain there, and snow, and all the other aerial
commotions which are natural to such a situation; and our idea of the
wisdom and power of God suggests to us, that he may have placed
creatures there to inhabit it.
The ancients, who had not the aid of the telescope, supplied the defect
of that instrument by extraordinary penetration. They deduced all those
consequences that are admitted by the moderns; for they discovered long
before, by the mental eye, whatever has since been presented to bodily
sight through the medium of telescopes. We have seen in how sublime a
manner they entered into the views of the Supreme Being in his
destination of the planets, and the multitude of stars placed by him in
the firmament. We have already seen, that they looked upon them as so
many suns, about which rolled planets of their own, such as those of our
solar system; maintaining that those planets contained inhabitants,
whose natures they presume not to describe, though they suppose them not
to yield to those of ours, either in beauty or dignity.
Orpheus is the earliest author whose opinion on this subject hath come
down to us. Proclus presents us with three verses of that eminent
ancient, wherein he positively asserts, that “the moon was another
earth, having in it mountains, vallies,” &c.
Pythagoras, who followed Orpheus in many of his opinions, taught
likewise, that “the moon was an earth like ours, replete with animals,
whose nature he presumed not to describe,” though he was persuaded they
were of a more noble and elegant kind than ours, and not liable to the
same infirmities.
Cicero ascribes a similar sentiment to Democritus, when, in explaining
his theory, he says, that, according to it, Quintus Luctatius Catulus,
for instance, might without end be multiplied into an infinity of
worlds. It were easy to multiply quotations, in proof that this opinion
was common among the ancient philosophers. There is a very remarkable
passage of Stobæus, wherein he gives us Democritus’s opinion about the
nature of the moon, and the cause of those spots which we see upon its
disk. That great philosopher imagined, that “those spots were no other
than shades, formed by the excessive height of the lunar mountains,”
which intercepted the light from the lower parts of that planet, where
the vallies formed themselves into what appeared to us as shades or
spots.
Plutarch went still farther, alleging, that there were embosomed in the
moon, vast seas and profound caverns. These, his conjectures, are built
upon the same foundation with those of the moderns. He says, that those
deep and extensive shades which appear upon the disk of that planet,
must be occasioned by the “vast seas” it contains, which are incapable
of reflecting so vivid a light, as the more solid and opaque parts; or
“by caverns extremely wide and deep, wherein the rays of the sun are
absorbed,” whence those shades and that obscurity which we call the
spots of the moon. Xenophanes said, that those immense cavities were
inhabited by another race of men, who lived there, as we do upon this
earth.
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