ut
of gear. Thus it is readily understood that mental unsoundness is an
affection of the brain, a bodily disease, which may often be relieved
and even cured by bodily remedies, by the use of drugs or wholesome
food, healthy exercise, fresh air, and all that benefits the nervous
system.

Pathologically considered, the nerves may be too excited or too sluggish
and torpid; and we have as the result two subdivisions of mental
insanity--_mania_ and _melancholia_. The differences between these two
are very striking; as they proceed from opposite causes they produce
opposite effects, and, therefore, they betray themselves by very
different manifestations; but in one point the two agree, and with this
point precisely we are concerned, because in it lies the essence of
mental insanity, namely, that both produce a disordered action of the
imagination.

3. The manner in which the imagination co-operates in mental action is
this. It presents to the intellect the materials from which that power
forms its ideas. When we see, feel, hear, taste, or smell anything by
our bodily senses, our imagination takes note of the object perceived by
forming a brain-picture of it which is called a _phantasm_. I do not
mean to say that it forms a photographic picture of the object; for
there can be no photographing taste or smell or feeling; but it forms an
image of some kind which it presents to the intellect. This power at
once proceeds to form, not a brain-picture, but an intellectual or
abstract image of the object presented. For instance, you see this book,
and at once you, in some mysterious way which has never yet been
explained, impress some image of it on your brain. That you do so is
clear from the fact that the image remains when the book is withdrawn.
That material image or brain-picture is the _phantasm_. It is not an
_idea_, though it is often improperly so called. But your intellect
forms to itself an idea of a book; that is, you know what is meant by a
book. You distinguish between the mere form of a book and the book
itself. Your idea of a book is a universal idea, which stands for any
book, no matter of what shape or size. Every phantasm, or brain-picture,
is a representation which presents its object as having a definite shape
or size, while your idea of a book ignores any shape or size. And yet,
when your intellect conceives a book, your imagination will picture some
particular form of book. If your brain became so affected by