he supposition that dogs form
generic ideas of sensible objects. One of the most curious peculiarities
of the dog mind is its inherent snobbishness, shown by the regard paid
to external respectability. The dog who barks furiously at a beggar will
let a well-dressed man pass him without opposition. Has he not then a
"generic idea" of rags and dirt associated with the idea of aversion,
and that of sleek broadcloth associated with the idea of liking?

In short, it seems hard to assign any good reason for denying to the
higher animals any mental state, or process, in which the employment of
the vocal or visual symbols of which language is composed is not
involved; and comparative psychology confirms the position in relation
to the rest of the animal world assigned to man by comparative anatomy.
As comparative anatomy is easily able to show that, physically, man is
but the last term of a long series of forms, which lead, by slow
gradations, from the highest mammal to the almost formless speck of
living protoplasm, which lies on the shadowy boundary between animal and
vegetable life; so, comparative psychology, though but a young science,
and far short of her elder sister's growth, points to the same
conclusion.

In the absence of a distinct nervous system, we have no right to look
for its product, consciousness; and, even in those forms of animal life
in which the nervous apparatus has reached no higher degree of
development, than that exhibited by the system of the spinal cord and
the foundation of the brain in ourselves, the argument from analogy
leaves the assumption of the existence of any form of consciousness
unsupported. With the super-addition of a nervous apparatus
corresponding with the cerebrum in ourselves, it is allowable to suppose
the appearance of the simplest states of consciousness, or the
sensations; and it is conceivable that these may at first exist, without
any power of reproducing them, as memories; and, consequently, without
ideation. Still higher, an apparatus of correlation may be superadded,
until, as all these organs become more developed, the condition of the
highest speechless animals is attained.

It is a remarkable example of Hume's sagacity that he perceived the
importance of a branch of science which, even now, can hardly be said to
exist; and that, in a remarkable passage, he sketches in bold outlines
the chief features of comparative psychology.

" ... any theory, by which we expl