ding, in which one hemisphere of the brain listens to the
romance suggestions of the other, though both well know that the subject
they are entertaining themselves with is a mere fiction. The strength
and precision of mental operations depend as much upon the complete
equivalency of the two lateral halves as upon their absolute
development. It is scarcely to be expected that great intellectual
indications will be given by him, one of whose cerebral hemispheres is
unequal to the other. But for the detailed consideration of these topics
I may refer the reader to my work on Physiology. He will there find the
explanation of the nature of registering ganglia; the physical theory of
memory; the causes of our variable psychical powers at different times;
the description of the ear as the organ of time; the eye as the organ of
space; the touch as that of pressures and temperatures; the smell and
taste as those for the chemical determination of gases and liquids.

[Sidenote: Conclusions from the foregoing anatomical facts.] From a
consideration of the construction, development, and action of the
nervous system of man, we may gain correct views of his relations to
other organic beings, and obtain true psychical and metaphysical
theories. There is not that homogeneousness in his intellectual
structure which writers on those topics so long supposed. It is a triple
mechanism. [Sidenote: Man a member of the animal series.] A gentle, a
gradual, a definite development reaches its maximum in him without a
breach of continuity. Parts which, because of their completion, are
capable of yielding in him such splendid results, are seen in a
rudimentary and useless condition in organisms very far down below. On
the clear recognition of this rudimentary, this useless state, very much
depends. It indicates the master-fact of psychology--the fact that
Averroes overlooked--that, while man agrees with inferior beings in the
type of his construction, and passes in his development through
transformations analogous to theirs, he differs from them all in this,
that he alone possesses an accountable, an immortal soul. It is true
that there are some which closely approach him in structure, but the
existence of structure by no means implies the exercise of functions. In
the still-born infant, the mechanism for respiration, the lungs, is
completed; but the air may never enter, and the intention for which they
were formed never be carried out.

[Sidenote: