s with so extraordinary a series
of gradations as this--leading us insensibly from the crown and summit
of the animal creation down to creatures, from which there is but a
step, as it seems, to the lowest, smallest, and least intelligent of
the placental Mammalia. It is as if nature herself had foreseen
the arrogance of man, and with Roman severity had provided that his
intellect, by its very triumphs, should call into prominence the slaves,
admonishing the conqueror that he is but dust.

These are the chief facts, this the immediate conclusion from them
to which I adverted in the commencement of this Essay. The facts, I
believe, cannot be disputed; and if so, the conclusion appears to me to
be inevitable.

But if Man be separated by no greater structural barrier from the brutes
than they are from one another--then it seems to follow that if any
process of physical causation can be discovered by which the genera
and families of ordinary animals have been produced, that process of
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