planetary system," he says, "there are the five following
phenomena: The movement of the planets in the
same direction and very nearly in the same plane; the
movement of the satellites in the same direction as
that of the planets; the rotation of these different
bodies and the sun in the same direction as their revolution,
and in nearly the same plane; the slight eccentricity of the
orbits of the planets and of the satellites;
and, finally, the great eccentricity of the orbits of the
comets, as if their inclinations had been left to chance.

"Buffon is the only man I know who, since the discovery
of the true system of the world, has endeavored
to show the origin of the planets and their satellites.
He supposes that a comet, in falling into the sun, drove
from it a mass of matter which was reassembled at a
distance in the form of various globes more or less
large, and more or less removed from the sun, and that
these globes, becoming opaque and solid, are now the
planets and their satellites.

"This hypothesis satisfies the first of the five preceding
phenomena; for it is clear that all the bodies
thus formed would move very nearly in the plane
which passed through the centre of the sun, and in the
direction of the torrent of matter which was produced;
but the four other phenomena appear to be inexplicable
to me by this means. Indeed, the absolute movement
of the molecules of a planet ought then to be in
the direction of the movement of its centre of gravity;