about it? The reasons for believing in such a conversion can
very well exist and at the same time escape your attention; and
it is not certain that your intelligence in this respect has
risen to the level of your experience. But, admitting the
negative argument of M. Liebig, what follows? That, with about
fifty-six exceptions, irreducible as yet, all matter is in a
condition of perpetual metamorphosis. Now, it is a law of our
reason to suppose in Nature unity of substance as well as unity
of force and system; moreover, the series of chemical compounds
and simple substances themselves leads us irresistibly to this
conclusion. Why, then, refuse to follow to the end the road
opened by science, and to admit an hypothesis which is the
inevitable result of experience itself?

M. Liebig not only denies the transmutability of elements, but
rejects the spontaneous formation of germs. Now, if we reject
the spontaneous formation of germs, we are forced to admit their
eternity; and as, on the other hand, geology proves that the
globe has not been inhabited always, we must admit also that, at
a given moment, the eternal germs of animals and plants were
born, without father or mother, over the whole face of the earth.

Thus, the denial of spontaneous generation leads back to the
hypothesis of spontaneity: what is there in much-derided
metaphysics more contradictory?

Let it not be thought, however, that I deny the value and
certainty of chemical theories, or that the atomic theory seems
to me absurd, or that I share the Epicurean opinion as to
spontaneous generation. Once more, all that I wish to point out