of the evolutionary
idea.

He starts from the fact that philosophers use the word development to
designate a definite sequence of ideas, i.e., in a logical order.
"Metamorphosis, says Hegel, belongs to the Idea as such since its
variation alone is development. Rational speculation must get rid of
such nebulous concepts as the evolution of the more highly developed
animal organisms from the less developed, etc."

Naturalists use the word in a different sense. Instead of a sequence of
grades of being they posit a sequence of transformations; instead of a
logical sequence of ideas they posit a transforming and progressive
development. Zoology constructs a system of specific and generic
concepts, "an animal kingdom with logical relations." Our concepts are
derived from natural objects, but in reality do not perfectly
correspond to them. The phylogenetic school commits the capital mistake
of presenting a transformation which can be realized only in logical
concepts, as an actually occurring process, and of confounding an
abstract operation with concrete fact. "The logical transformation of
the concept ape into the concept man is no genealogical process." The
mathematician may logically 'develop' the concept of a circle from that
of a polygon, but it by no means follows that the circle is
phylo-genetically derived from the polygon.

Because the concept of species is variable, the species themselves,
according to Darwin, should be subject to a continual flux; whereas the
real cause of the variability which he observed lies in the discrepancy
between objective facts and their logical tabulation, in the narrowness
of our concepts and in the lack of adequate means of expression. He
thus makes natural objects responsible for our logical limitations.

With regard to organisms the Descent-school confounded the purely
logical signification of the word "related" with that of blood or
family affinity. But surely when they speak of the relation of forms in
the crystal systems, they do not refer to genetic connection. To-day
this interchange of concepts is so general that one needs to exercise
great care if one would avoid it.

The theory which postulates the blood-relationship of individuals of
the same species may be correct, but it is utterly incapable of proof,
and the same is true in a greater degree when there is question of
individuals of the same class but of different species. Since a direct
proof is impossible, an attemp