reak in the chain of
thought, because the law of the logical process forbids it: there can be
no break in the series of material symbols for the conditions of
concrete expression equally forbid it. A symbol is nothing except as it
represents that which is to be symbolized. So the symbols form a
physical series, because the thoughts symbolized form a logical series.

If the creator has fully revealed his thought, it must be by a series of
physical terms arranged in such a manner as to indicate the logical
series of ideas symbolized. Every form of matter is a symbol of thought,
and challenges interpretation. Every change in form corresponds to an
antecedent change in idea, and must be intended to reveal it. As
thought, then, begins its evolution with the general and proceeds to the
individual by a series of terms each of which is similarly related to
both extremes, we must find the material enunciation of this process
assuming the form of a series of terms, beginning with mere nebulous
matter, grading into organic life, and organic life presenting us with a
similar series beginning with the mere cell and ending with man. So
rigid and invariable must this serial arrangement be that if a term in
either series be wanting, we are authorized to hypothetically
interpolate it.

"Nature never makes a leap," says the scientific investigator, as he
studies the material symbols of thought. "Thought never makes a leap,"
says the metaphysician, as he studies the necessary laws of rational
action: and both have uttered the same truth. We prove a proposition by
determining the steps by which it was educed from a more generic
statement. Science must proceed in the same manner, for science only
discovers the track of mind--it does not make the track, it only follows
it. If then we find the chain of evolution broken at any point, science
must either stop there, or assume the wanting term in the series. We
have the right to interpolate these missing terms, for we must assume
that the thoughts of God communicated to us in material forms constitute
a continuous revelation, beginning with Himself, the final
generalization, and ending with man the highest individualization. These
limits are fixed--the one by the nature of God, and the other by the
nature of man. Between these two extremes we must find a series of
intermediate terms. Any other conception of their relation than that of
a determinate series is impossible and irrational; and a ser