not as well form separately an indefinite
number of creatures of the same species as a single pair. This point is
not adverted to in the work before us; and whenever identity of origin
is assumed, it is upon the same grounds from which identity of species
is deduced. In fact, they are generally coupled; thus, at page 487, we
have the expression--

"If now it should appear, on enquiry, that one common mind, or
psychical nature, belongs to the whole human family, a very strong
argument would thence arise, on the ground of analogy, for their
community of species and origin."

And in the last page we have--

"We are entitled to draw confidently the conclusion, that all human
races are of one species and one family."

The great point as to identity of species being proved, it would be
certainly more simple, and more in unison with the economy of nature, to
suppose that all were descended from one pair, than that numerous
identical members of a common species were simultaneously created. On
the other hand, a physiological difficulty occurs, in viewing a race as
descended from a single pair, from the fact universally recognised in
the later periods of history, viz. the degeneration, and, in the end,
destruction or indefinite deterioration of both physical and mental
faculties, by continual intermarriage. The houses of Braganza and
Hapsburg are notorious instances of this; and, as far as we are aware,
there are no counter instances.

"Marry
A gentler scion to the wildest stock,
And make conceive a bark of baser kind
By bud of nobler race; this is an art
Which does mend nature, change it rather, but
The art itself is nature."

The matter is incapable of absolute proof--we mean inductive proof; for
it is in this point that the work before us regards it. Any arguments,
such as similarity of habits, of languages, of opinions, which may be
used to deduce community of origin, would be equally explained by
community of species; for, supposing that different individuals of the
same species were simultaneously created, the same physical formation
would necessarily engender similar habits, and the power of
intermarriage would induce a similarity of language, long before any
period to which our histories go back. Taking, then, as a fair
assumption, that, if identical in species, mankind have a common origin,
we get in the outset of the book the conclusio