well-tried courage--physical, intellectual, and moral--would have
been equal to this feat. No doubt the sudden concurrence of
half-a-ton of inorganic molecules into a live rhinoceros is
conceivable, and therefore may be possible. But does such an
event lie sufficiently within the bounds of probability to
justify the belief in its occurrence on the strength of any
attainable, or, indeed, imaginable, evidence?

In view of the assertion (often repeated in the early days of the
opposition to Darwin) that he had added nothing to Lamarck, it is
very interesting to observe that the possibility of a fifth
alternative, in addition to the four he has stated, has not
dawned upon Dr. Whewell's mind. The suggestion that new species
may result from the selective action of external conditions upon
the variations from their specific type which individuals
present--and which we call "spontaneous," because we are ignorant
of their causation--is as wholly unknown to the historian of
scientific ideas as it was to biological specialists before 1858.
But that suggestion is the central idea of the 'Origin of
Species,' and contains the quintessence of Darwinism.

Thus, looking back into the past, it seems to me that my own
position of critical expectancy was just and reasonable, and must
have been taken up, on the same grounds, by many other persons.
If Agassiz told me that the forms of life which had successively
tenanted the globe were the incarnations of successive thoughts
of the Deity; and that he had wiped out one set of these
embodiments by an appalling geological catastrophe as soon as His
ideas took a more advanced shape, I found myself not only unable
to admit the accuracy of the deductions from the facts of