causation is amply sufficient to account for the origin of Man. In
other words, if it could be shown that the Marmosets, for example, have
arisen by gradual modification of the ordinary Platyrhini, or that both
Marmosets and Platyrhini are modified ramifications of a primitive
stock--then, there would be no rational ground for doubting that man
might have originated, in the one case, by the gradual modification of
a man-like ape; or, in the other case, as a ramification of the same
primitive stock as those apes.

At the present moment, but one such process of physical causation has
any evidence in its favour; or, in other words, there is but one
hypothesis regarding the origin of species of animals in general which
has any scientific existence--that propounded by Mr. Darwin. For
Lamarck, sagacious as many of his views were, mingled them with so much
that was crude and even absurd, as to neutralize the benefit which his
originality might have effected, had he been a more sober and cautious
thinker; and though I have heard of the announcement of a formula
touching "the ordained continuous becoming of organic forms," it is
obvious that it is the first duty of a hypothesis to be intelligible,
and that a qua-qua-versal proposition of this kind, which may be read
backwards, or forwards, or sideways, with exactly the same amount of
signification, does not really exist, though it may seem to do so.

At the present moment, therefore, the question of the relation of man to
the lower animals resolves itself, in the end, into the larger question
of the tenability, or untenability of Mr. Darwin's views. But here we
enter upon difficult ground, and it behoves us to define our exact
position with the greatest care.

It cannot be doubted, I think, that Mr. Darwin has satisfactorily proved