Yet who can doubt that, whenever a sufficiently extensive series
of lacustrine and fluviatile beds of that age becomes known, the
lineage which has been traced thus far will be continued by
equine quadrupeds with an increasing number of digits, until the
horse type merges in the five-toed form towards which these
gradations point?

But the argument which holds good for the horse, holds good, not
only for all mammals, but for the whole animal world. And as the
study of the pedigrees, or lines of evolution, to which, at
present, we have access, brings to light, as it assuredly will
do, the laws of that process, we shall be able to reason from
the facts with which the geological record furnishes us to those
which have hitherto remained, and many of which, perhaps, may
for ever remain, hidden. The same method of reasoning which
enables us, when furnished with a fragment of an extinct animal,
to prophesy the character which the whole organism exhibited,
will, sooner or later, enable us, when we know a few of the
later terms of a genealogical series, to predict the nature of
the earlier terms.

In no very distant future, the method of Zadig, applied to a
greater body of facts than the present generation is fortunate
enough to handle, will enable the biologist to reconstruct the
scheme of life from its beginning, and to speak as confidently
of the character of long extinct beings, no trace of which has
been preserved, as Zadig did of the queen's spaniel and the
king's horse. Let us hope that they may be better rewarded for
their toil and their sagacity than was the Babylonian
philosopher; for perhaps, by that time, the magi also may be