orehand, those bodies lost for ever their
ancient prestige. The most timid minds troubled themselves quite as
little about them as about eclipses of the sun and moon, which are
equally subject to calculation. In fine, the labours of Clairaut had
produced a deeper impression on the public mind than the learned,
ingenious, and acute reasoning of Bayle.

The heavens offer to reflecting minds nothing more curious or more
strange than the equality which subsists between the movements of
rotation and revolution of our satellite. By reason of this perfect
equality the moon always presents the same side to the earth. The
hemisphere which we see in the present day is precisely that which our
ancestors saw in the most remote ages; it is exactly the hemisphere
which future generations will perceive.

The doctrine of final causes which certain philosophers have so
abundantly made use of in endeavouring to account for a great number of
natural phenomena was in this particular case totally inapplicable. In
fact, how could it be pretended that mankind could have any interest in
perceiving incessantly the same hemisphere of the moon, in never
obtaining a glimpse of the opposite hemisphere? On the other hand, the
existence of a perfect, mathematical equality between elements having no
necessary connection--such as the movements of translation and rotation
of a given celestial body--was not less repugnant to all ideas of
probability. There were besides two other numerical coincidences quite
as extraordinary; an identity of direction, relative to the stars, of
the equator and orbit of the moon; exactly the same precessional
movements of these two planes. This group of singular phenomena,
discovered by J.D. Cassini, constituted the mathematical code of what is
called the _Libration of the Moon_.

The libration of the moon formed a very imperfect part of physical
astronomy when Lagrange made it depend on a circumstance connected with
the figure of our satellite which was not observable from the earth, and
thereby connected it completely with the principles of universal
gravitation.

At the time when the moon was converted into a solid body, the action of
the earth compelled it to assume a less regular figure than if no
attracting body had been situate in its vicinity. The action of our
globe rendered elliptical an equator which otherwise would have been
circular. This disturbing action did not prevent the lunar equator from
bulging out