g of the way in which even the races of mankind have
struggled and crowded each other out, Buffon says:--

"These great events--these well-marked epochs in the history of the
human race--are yet but ripples, as it were, on the current of life;
which, as a general rule, flows onward evenly and in equal volume.

"It may be said that the movement of Nature turns upon two immovable
pivots--one, the illimitable fecundity which she has given to all
species; the other, the innumerable difficulties which reduce the
results of that fecundity, and leave throughout time nearly the same
quantity of individuals in every species.[89]... Taking the earth as a
whole, and the human race in its entirety, the numbers of mankind, like
those of animals, should remain nearly constant throughout time; for
they depend upon an equilibrium of physical causes which has long since
been reached, and which neither man's moral nor his physical efforts can
disturb, inasmuch as these moral efforts do but spring from physical
causes, of which they are the special effects. No matter what care man
may take of his own species, he can only make it more abundant in one
place by destroying it or diminishing its numbers in another. When one
part of the globe is overpeopled, men emigrate, spread themselves over
other countries, destroy one another, and establish laws and customs
which sometimes only too surely prevent excess of population. In those
climates where fecundity is greatest, as in China, Egypt, and Guinea,
they banish, mutilate, sell, or drown infants. Here, we condemn them to
a perpetual celibacy. Those who are in being find it easy to assert
rights over the unborn. Regarding themselves as the necessary, they
annihilate the contingent, and suppress future generations for their own
pleasure and advantage. Man does for his own race, without perceiving
it, what he does also for the inferior animals: that is to say, he
protects it and encourages it to increase, or neglects it according to
his sense of need--according as advantage or inconvenience is expected
as the consequence of either course. And since all these moral effects
themselves depend upon physical causes, which have been in permanent
equilibrium ever since the world was formed, it follows that the numbers
of mankind, like those of animals, should remain constant.

"Nevertheless, this fixed state, this constant number, is not absolute,
all physical and moral causes, and all the results which