parchus was the first among the Greeks who observed some change in the
constellations with regard to the equinoxes, or rather who learnt it from
the Egyptians. Philosophers ascribed this motion to the stars; for in
those ages people were far from imagining such a revolution in the earth,
which was supposed to be immovable in every respect. They therefore
created a heaven in which they fixed the several stars, and gave this
heaven a particular motion by which it was carried towards the east,
whilst that all the stars seemed to perform their diurnal revolution from
east to west. To this error they added a second of much greater
consequence, by imagining that the pretended heaven of the fixed stars
advanced one degree eastward every hundred years. In this manner they
were no less mistaken in their astronomical calculation than in their
system of natural philosophy. As for instance, an astronomer in that age
would have said that the vernal equinox was in the time of such and such
an observation, in such a sign, and in such a star. It has advanced two
degrees of each since the time that observation was made to the present.
Now two degrees are equivalent to two hundred years; consequently the
astronomer who made that observation lived just so many years before me.
It is certain that an astronomer who had argued in this manner would have
mistook just fifty-four years; hence it is that the ancients, who were
doubly deceived, made their great year of the world, that is, the
revolution of the whole heavens, to consist of thirty-six thousand years.
But the moderns are sensible that this imaginary revolution of the heaven
of the stars is nothing else than the revolution of the poles of the
earth, which is performed in twenty-five thousand nine hundred years. It
may be proper to observe transiently in this place, that Sir Isaac, by
determining the figure of the earth, has very happily explained the cause
of this revolution.

All this being laid down, the only thing remaining to settle chronology
is to see through what star the colure of the equinoxes passes, and where
it intersects at this time the ecliptic in the spring; and to discover
whether some ancient writer does not tell us in what point the ecliptic
was intersected in his time, by the same colure of the equinoxes.

Clemens Alexandrinus informs us, that Chiron, who went with the
Argonauts, observed the constellations at the time of that famous
expedition, and fixed th