It must not be supposed that in this primary fact, and in these _a
priori_ psychical and organic conditions, we shall find the ulterior
cause of the various and manifold forms, or of the successive evolution
of myths. This would be a grave mistake, equal to that of
transcendentalists, who imagine that the laws which actually exist, and
the order of cosmic and historic phenomena may be determined from the
independent exercise of their own thoughts, although such laws and order
can only be traced and discovered by experience and the observation of
facts. In the _a priori_ conditions of the psychical and organic nature,
and in the elementary acts which outwardly result from them, we shall
only trace the origin and necessary source of myth, not the variable
forms of its successive evolution.

The ulterior form, so far as the substance of the myth and its various
modifications are concerned, is in great part the reflex work of man;
its aspect changes in accordance with the attitude and force of the
faculties of individuals, peoples and races, and it depends on an energy
to which the _a priori_ conditions, as we have just defined them, do not
strictly apply so far as the determinate form is concerned.

It is precisely in this ulterior work of the evolution of myth, which in
the elementary fact of its primitive essence had its origin in the
predisposition of mind and body, that we may discern the interchangeable
germ and origin both of myth and science. If, therefore; the rationale
of science cannot be found in the general form of mythical
representations, the matter which serves to exercise the mind; yet the
mode of its exercise, and of the logical and psychical faculty, and the
spontaneous method pursued, are identical: the two mythical and
scientific faculties are, in fact, considered in themselves, fused into
one.