that it makes many
assumptions, some of which rest without any proof, and others are known
to be false.

When were the planets discovered? Not certainly at the dawn of
astronomy. The fixed stars must have become familiar, and have been
recognized in their various groupings before it could have been known
that there were others that were not fixed,--were "planets," _i. e._
wanderers. Thus, amongst the Greeks, no planet is alluded to by Hesiod,
and Homer mentions no planet other than Venus, and apparently regarded
her as two distinct objects, according as she was seen as a morning and
as an evening star. Pythagoras is reputed to have been the first of the
Greek philosophers to realize the identity of Phosphorus and Hesperus,
that is Venus at her two elongations, so that the Greeks did not know
this until the sixth century before our era. We are yet without certain
knowledge as to when the Babylonians began to notice the different
planets, but the order of discovery can hardly have been different from
what it seems to have been amongst the Greeks--that is to say, first
Venus as two separate objects, then Jupiter and Mars, and, probably much
later, Saturn and Mercury. This last, again, would originally be
considered a pair of planets, just as Venus had been. Later these
planets as morning stars would be identified with their appearances as
evening stars. After this obscurity had been cleared up, there was a
still further advance to be made before the astrologers could have
adopted their strange grouping of the sun and moon as planets equally
with the other five. This certainly is no primitive conception; for the
sun and moon have such appreciable dimensions and are of such great
brightness that they seem to be marked off (as in the first chapter of
Genesis) as of an entirely different order from all the other heavenly
bodies. The point in common with the other five planets, namely their
apparent periodical movements, could only have been brought out by very
careful and prolonged observation. The recognition, therefore, of the
planets as being "seven," two of the seven being the sun and moon, must
have been quite late in the history of the world. The connection of the
"seven planets" with the seven days of the week was something much later
still. It implies, as we have seen, the adoption of a particular order
for the planets, and this order further implies that a knowledge had
been obtained of their relative distances, and