which led to the construction
of the biogenetic law were discovered in no small measure by Agassiz, who
was an opponent of the doctrine of descent.(31)

But the advance from the doctrine of evolution to that of descent was
imperatively prompted by a recognition of the fact that the earth is not
from everlasting, and that the forms of life upon it are likewise not from
everlasting, that, in fact, their several grades appear in an orderly
ascending series. It is therefore simpler and more plausible to suppose
that each higher step has arisen from the one before it, than to suppose
that each has, so to speak, begun an evolution on its own account. A
series of corroborative arguments might be adduced, and there is no doubt,
as we have said before, that the transition from the general idea of
evolution to that of descent will be fully accomplished. But it is plain
that the special idea of descent contributes nothing essentially new on
the subject.

It is an oft-repeated and self-evident statement, that it is in reality a
matter of entire indifference whether man arose from the dust of the earth
or from living matter already formed, or, let us say, from one of the
higher vertebrates. The question still would be, how much or how little of
any of them does he still retain, and how far does he differ from all?
Even if there be really descent, the difference may quite as well be so
great--for instance, through saltatory development--that man, in spite of
physical relationship, might belong to quite a new category far
transcending all his ancestors in his intellectual characteristics, in his
emotional and moral qualities. There is nothing against the assumption,
and there is much to be said in its favour, that the last step from animal
to man was such an immense one that it brought with it a freedom and
richness of psychical life incomparable with anything that had gone
before--as if life here realised itself for the first time in very truth,
and made everything that previously had been a mere preliminary play.

On the other hand, even were there no descent but separate individual
creation, man might, in virtue of his ideal relationship and evolution,
appear nothing more than a stage relatively separate from those beneath
him in evolution. It was not the doctrine of descent, it was the doctrine
of evolution that first ranked man in a series with the rest of creation,
and regarded him as the development of what is beneath him and