arked the
twelve signs of the zodiac amongst the Chaldaeans. But under this
supposition the twenty-eight has no reference to the moon, whereas we
have every reason to believe it has.' The last observation is
undoubtedly correct--the twenty-eight mansions have been mansions of the
moon from the beginning. But in this very circumstance, as also in the
very tablets referred to in the preceding passage, we find all the
evidence needed to show that originally the Chaldaeans divided the
zodiac into twenty-eight parts. For we find from the tablets that, like
the other nations who had twenty-eight zodiacal mansions, the Chaldaeans
used a seven-day period, derived from the moon's motions, every seventh
day being called _sabbatu_, and held as a day of rest. We may safely
infer that the Chaldaean astronomers, advancing beyond those of other
nations, recognised the necessity of dividing the zodiac with reference
to the sun's motions instead of the moon's. They therefore discarded the
twenty-eight lunar mansions, and adopted instead twelve solar signs;
this number twelve, like the number twenty-eight itself, being selected
merely as the most convenient approximation to the number of parts into
which the zodiac was naturally divided by another period. Thus the
twenty-eighth part of the zodiac corresponds roughly with the moon's
daily motion, and the twelfth part of the zodiac corresponds roughly
with the moon's monthly motion; and both the numbers twenty-eight and
twelve admit of being subdivided, while twenty-nine (a nearer approach
than twenty-eight to the number of days in a lunation) and thirteen
(almost as near an approach as twelve to the number of months in a year)
do not.

It seems to me highly probable that the date to which all inquiries into
the origin of the constellations and the zodiacal signs seems to
point--viz. 2170 B.C.--was the date at which the Chaldaean astronomers
definitely adopted the new system, the lunisolar instead of lunar
division of the zodiac and of time. One of the objects which the
architects of the Great Pyramid (not the king who built it) may have had
was not improbably this--the erection of a building indicating the epoch
when the new system was entered upon, and defining in its proportions,
its interior passages, and other features, fundamental elements of the
new system. The great difficulty, an overwhelming difficulty it has
always seemed to me, in accepting the belief that the year 2170 B.C.
d