l facts is, that an
increase in the diversity of types both of plants and animals has been
constant and progressive from the earliest to the latest times, as we
should anticipate that it must have been on the theory of descent in
ever-ramifying lines of pedigree. And the second general fact is, that
through all these branching lines of ever-multiplying types, from the
first appearance of each of them to their latest known conditions, there
is overwhelming evidence of one great law of organic nature--the law of
gradual advance from the general to the special, from the low to the
high, from the simple to the complex.

Now, the importance of these large and general facts in the present
connexion must be at once apparent; but it may perhaps be rendered more
so if we try to imagine how the case would have stood supposing
geological investigation to have yielded in this matter an opposite
result, or even so much as an equivocal result. If it had yielded an
opposite result, if the lower geological formations were found to
contain as many, as diverse, and as highly organized types as the later
geological formations, clearly there would have been no room at all for
any theory of progressive evolution. And, by parity of reasoning, in
whatever degree such a state of matters were found to prevail, in that
degree would the theory in question have been discredited. But seeing
that these opposite principles do not prevail in any (relatively
speaking) considerable degree[16], we have so far positive testimony of
the largest and most massive character in favour of this theory. For
while all these large and general facts are very much what they ought to
be according to this theory, they cannot be held to lend any support at
all to the rival theory. In other words, it is clearly no essential part
of the theory of special creation that species should everywhere exhibit
this gradual multiplication as to number, coupled with a gradual
diversification and general elevation of types, in all the growing
branches of the tree of life. No one could adopt seriously the jocular
lines of Burns, to the effect that the Creator required to practise his
prentice hand on lower types before advancing to the formation of
higher. Yet, without some such assumption, it would be impossible to
explain, on the theory of independent creations, why there should have
been this gradual advance from the few to the many, from the general to
the special, from the low to