form new beings. The attentive observer sees this law execute itself, in
a manner more or less prominent, through all the beings by which he is
surrounded. He sees nature full of _erratic germe_, some of which expand
themselves, whilst others wait until motion has placed them in their
proper situation, in suitable wombs or matrices, in the necessary
circumstances, to unfold, to increase, to render them more perceptible
by the addition of other substances of matter analogous to their
primitive being. In all this we see nothing but the effect of motion,
necessarily guided, modified, accelerated or slackened, strengthened or
weakened, by reason of the various properties that beings successively
acquire and lose; which, every moment, infallibly produces alterations
in bodies more or less marked. Indeed, these bodies cannot be, strictly
speaking, the same in any two successive moments of their existence;
they must, every instant, either acquire or lose: in short, they are
obliged to undergo continual variations in their essences, in their
properties, in their energies, in their masses, in their qualities, in
their mode of existence.

Animals, after they have been expanded in, and brought out of, the wombs
that are suitable to the elements of their machine, enlarge, strengthen,
acquire new properties, new energies, new faculties; either by deriving
nourishment from plants analogous to their being, or by devouring other
animals whose substance is suitable to their preservation; that is to
say, to repair the continual deperdition or loss of some portion of
their own substance, that is disengaging itself every instant. These
same animals are nourished, preserved, strengthened, and enlarged, by
the aid of air, water, earth, and fire. Deprived of air, or of the fluid
that surrounds them, that presses on them, that penetrates them, that
gives them their elasticity, they presently cease to live. Water,
combined with this air, enters into their whole mechanism of which it