Such is the constant, the invariable course, of Nature; such is the
eternal circle of mutation, which all that exists is obliged to
describe. It is thus motion generates, preserves for a time, and
successively, destroys, one part of the universe by the other; whilst
the sum of existence remains eternally the same. Nature, by its
combinations, produces suns, which place themselves in the centre of so
many systems: she forms planets, which, by their peculiar essence,
gravitate and describe their revolutions round these suns: by degrees
the motion is changed altogether, and becomes eccentric: perhaps the day
may arrive when these wondrous masses will disperse, of which man, in
the short space of his existence, can only have a faint and transient
glimpse.

It is clear, then, that the continual motion inherent in matter, changes
and destroys all beings; every instant depriving them of some of their
properties, to substitute others: it is motion, which, in thus changing
their actual essence, changes also their order, their direction, their
tendency, and the laws which regulate their mode of acting and being:
from the stone formed in the bowels of the earth, by the intimate
combination and close coherence of similar and analogous particles, to
the sun, that vast reservoir of igneous particles, which sheds torrents
of light over the firmament; from the benumbed oyster, to the thoughtful
and active man; we see an uninterrupted progression, a perpetual chain
of motion and combination; from which is produced, beings that only
differ from each other by the variety of their elementary matter--by the
numerous combinations of these elements, from whence springs modes of
action and existence, diversified to infinity. In generation, in
nutrition, in preservation, we see nothing more than matter, variously
combined, of which each has its peculiar motion, regulated by fixed and