us size. The heliocentric system,
thus regarding the sun as the central orb, degraded the earth to a very
subordinate rank, making her only one of a company of six revolving
bodies.

But this is not the only contribution conferred on astronomy by
Aristarchus, for, considering that the movement of the earth does not
sensibly affect the apparent position of the stars, he inferred that
they are incomparably more distant from us than the sun. He, therefore,
of all the ancients, as Laplace remarks, had the most correct ideas of
the grandeur of the universe. He saw that the earth is of absolutely
insignificant size, when compared with the stellar distances. He saw,
too, that there is nothing above us but space and stars.

But the views of Aristarchus, as respects the emplacement of the
planetary bodies, were not accepted by antiquity; the system proposed by
Ptolemy, and incorporated in his "Syntaxis," was universally preferred.
The physical philosophy of those times was very imperfect--one of
Ptolemy's objections to the Pythagorean system being that, if the earth
were in motion, it would leave the air and other light bodies behind it.
He therefore placed the earth in the central position, and in succession
revolved round her the Moon, Mercury, Venus, the Sun, Mars, Jupiter,
Saturn; beyond the orbit of Saturn came the firmament of the fixed
stars. As to the solid crystalline spheres, one moving from east to
west, the other from north to south, these were a fancy of Eudoxus, to
which Ptolemy does not allude.

The Ptolemaic system is, therefore, essentially a geocentric system. It
left the earth in her position of superiority, and hence gave no cause
of umbrage to religious opinions, Christian or Mohammedan. The immense
reputation of its author, the signal ability of his great work on the
mechanism of the heavens, sustained it for almost fourteen hundred
years--that is, from the second to the sixteenth century.

In Christendom, the greater part of this long period was consumed
in disputes respecting the nature of God, and in struggles for
ecclesiastical power. The authority of the Fathers, and the prevailing
belief that the Scriptures contain the sum, of all knowledge,
discouraged any investigation of Nature. If by chance a passing interest
was taken in some astronomical question, it was at once settled by
a reference to such authorities as the writings of Augustine or
Lactantius, not by an appeal to the phenomena of the hea