however slight, B may no longer be that form which is best adapted to
withstand their destructive, and profit by their sustaining, influence; in
which case if it should give rise to a more competent variety (C), this
will take its place and become a new species; and thus, by natural
selection, the species B and C will be successively derived from A.

That this most ingenious hypothesis enables us to give a reason for many
apparent anomalies in the distribution of living beings in time and space,
and that it is not contradicted by the main phenomena of life and
organisation appear to us to be unquestionable; and, so far, it must be
admitted to have an immense advantage over any of its predecessors. But it
is quite another matter to affirm absolutely either the truth or falsehood
of Mr. Darwin's views at the present stage of the inquiry. Goethe has an
excellent aphorism defining that state of mind which he calls "Thaetige
Skepsis"--active doubt. It is doubt which so loves truth that it neither
dares rest in doubting, nor extinguish itself by unjustified belief; and we
commend this state of mind to students of species, with respect to Mr.
Darwin's or any other hypothesis, as to their origin. The combined
investigations of another twenty years may, perhaps, enable naturalists to
say whether the modifying causes and the selective power, which Mr. Darwin
has satisfactorily shown to exist in Nature, are competent to produce all
the effects he ascribes to them; or whether, on the other hand, he has been
led to over-estimate the value of the principle of natural selection, as
greatly as Lamarck over-estimated his _vera causa_ of modification by
exercise.

But there is, at all events, one advantage possessed by the more recent
writer over his predecessor. Mr. Darwin abhors mere speculation as nature
abhors a vacuum. He is as greedy of cases and precedents as any
constitutional lawyer, and all the principles he lays down are capable of