to rise at sunset. The grouping of the stars into constellations and
recording their places was a useful observation. The theoretical
prediction of eclipses of the sun and moon, and of the motions of the
planets among the stars, became later the highest goal in astronomy.

To not one of the above important steps in the progress of astronomy
can we assign the author with certainty. Probably many of them were
independently taken by Chinese, Indian, Persian, Tartar, Egyptian,
Babylonian, Assyrian, Phoenician, and Greek astronomers. And we have
not a particle of information about the discoveries, which may have
been great, by other peoples--by the Druids, the Mexicans, and the
Peruvians, for example.

We do know this, that all nations required to have a calendar. The
solar year, the lunar month, and the day were the units, and it is
owing to their incommensurability that we find so many calendars
proposed and in use at different times. The only object to be attained
by comparing the chronologies of ancient races is to fix the actual
dates of observations recorded, and this is not a part of a history of
astronomy.

In conclusion, let us bear in mind the limited point of view of the
ancients when we try to estimate their merit. Let us remember that the
first astronomy was of two dimensions; the second astronomy was of
three dimensions, but still purely geometrical. Since Kepler's day we
have had a dynamical astronomy.


FOOTNOTES: