brain at all, exhibit high intelligence; and some animals with smaller
brains are more docile and intelligent than others with a much larger
development. The ape, in spite of his close physical approach to the
structure of man, and his still greater relative distance from the other
animal creation, is not superior (if he is not decidedly inferior) in
reason or intelligence to several animals lower down in the scale.

Savages, again, have a brain greatly in excess of their actual
requirements (so to speak). Hence the mere existence of brain, however
complex, does not indicate the possession of mental power.

There is reason to believe that all thought and exercise of the mind--in
fact, every step in the process of "Education," whereby an ignorant
person is brought at last to apprehend the most abstract
propositions--is accompanied by some molecular (or other) change. So
that a person who has been carefully educated has the brain in a
different state from that of an exactly similarly constituted person
whose brain has been subjected to no such exercise. But even if this
action could be formulated and explained, it would not follow that
thought is the _product_ of the molecular change; or that, _vice versâ_,
if we could artificially produce certain changes, in the brain, certain
thoughts and perceptions would thereon coexist with the changes, and
arise in the mind of the subject forthwith. And if not, then no process
of physical development accounts for grades of intellect; we have only
mind developing as mind. But the theory of evolution will have nothing
to do with any development but physical; or at any rate with mental
development except as the result of physical: it knows nothing of pure
mind, or spiritual existence, or anything of the sort.

In the nature of things we can have neither observation nor experiment