rine of the descent of species which permit
this descent to take place, not by the leaps of a metamorphosis of germs,
but by transitions so imperceptably small that the difference of two
generations which lie in the same line of descent, is never greater than
those differences which always take place between parents and children of
the same species--transitions so gradual that only the continuation of
these individual changes in a single direction produces an increase and,
finally and gradually, the new species. The treatment of the question as to
what position this _evolution theory_ takes regarding theism, is even more
simple than answering the question as to the position of the descent idea
in reference to theism.

For now we have no longer to discuss the different possibilities of a
development, as heretofore we have discussed those of a descent, but only
the idea of a gradual development or of an evolution in general. Of such
possibilities, it is true, we find several. In the first place, we can look
for the inciting principle of the development of species either in the
interior of organisms, or we can see it approaching the latter from
without. The only scientific system which has made any attempt at
mentioning and elaborating the inciting principle of development is that of
Darwin; a system that chooses the second of the alternatives just stated
and sees the essential principle that makes the transmission of individuals
a progress beyond one species, approaching the individuals from without.
But while we shall have to treat of this specific Darwinian theory--the
selection theory--still more in detail in the following section, we shall
also there have to point, out {265} everything that theism has to say in
reference to a principle of development which approaches the organisms from
without. Another possible explanation of the origin of species through
development is to be found in the fact that we look for the inciting
principle of development in the interior of organisms. This is done, so far
as we know, by all those scientists who, although inclined to an evolution
theory, are adversaries of the selection theory; but none of them claim to
have found the inciting agencies of development. Thus, as in the preceding
section, we are again referred only to the wholly abstract possibility of
conceiving these inciting agencies either as coming into existence anew in
the organism with each smallest individual modification