have not referred to metaphysics, or
psychology, or mental philosophy. Cultivated as they have been, it was
not possible for them to yield any other result than they did among the
Greeks. A lever is no mechanical power unless it has a material point of
support. It is only through the physical that the metaphysical can be
discovered.

[Sidenote: Necessity of resorting to Anatomy and Physiology.] An
exposition of the structure, the physical forces, and the intellectual
operations of man must be founded on anatomy. We can only determine the
methods of action from the study of the mechanism, and the right
interpretation of that mechanism can only be ascertained from the
construction of its parts, from observations of the manner in which they
are developed, from comparisons with similar structures in other
animals, not rejecting even the lowest, and from an investigation of
their habits and peculiarities. Believing that, in the present state of
science, doctrines in psychology, unless they are sustained by evidence
derived from anatomy and physiology, are not to be relied on, I have not
thought it necessary to devote much space to their introduction. They
have not taken a part in the recent advances of humanity. They belong to
an earlier social period, and are an anachronism in ours. I have
referred to these points heretofore in my work on Physiology, and
perhaps shall be excused the following extract:

"The study of this portion of the mechanism of man brings us therefore
in contact with metaphysical science, and some of its fundamental dogmas
we have to consider. Nearly all philosophers who have cultivated in
recent times that branch of knowledge, have viewed with apprehension the
rapid advances of physiology, foreseeing that it would attempt the final
solution of problems which have exercised the ingenuity of the last
twenty centuries. [Sidenote: Solution of psychological questions.] In
this they are not mistaken. Certainly it is desirable that some new
method should be introduced, which may give point and precision to
whatever metaphysical truths exist, and enable us to distinguish,
separate, and dismiss what are only vain and empty speculations.

[Sidenote: Uncertainty of metaphysics.] "So far from philosophy being a
forbidden domain to the physiologist, it may be asserted that the time
has now come when no one is entitled to express an opinion in philosophy
unless he has first studied physiology. It has hitherto been