The brain is the mind. When the brain is diseased the mind is diseased.
When the brain is sick the mind is sick.
But the brain is part of the body. We see, hear, smell, feel, and taste
with the brain. The nerves of the toes and fingers are connected with
the brain; they are like twigs on a tree, of which the brain is the
root. The same blood which circulates through the heart and limbs
circulates through the brain.
It is only a figure of speech to speak of the mind and the body as
distinct from each other. The mind and the body are one.
A wound in any part of the body--a burn, a stab, a lash--is felt in the
brain. When the body suffers from illness or fatigue, the brain suffers
also. When a limb is paralysed, the real paralysis is in a part of the
brain. When the brain is paralysed the man can neither move nor speak,
nor think nor feel. When the heart is weak the brain does not get enough
blood, and the mind is languid, or syncope sets in ana the man dies.
We do not need a prophet nor a doctor to tell us that sickness affects
the mind. We know that dyspepsia, gout, or sluggish liver makes us
peevish, stupid, jealous, suspicious, and despondent.
We know that illness or weariness turns a sweet temper sour, makes a
patient man impatient, a grateful man ungrateful. We know how trying are
the caprices and whims of an invalid, and we commonly say of such, "he
cannot help it: he is not himself to-day."
But we do not know, as doctors know, how searching and how terrible are
the effects of some diseases on the brain. Dr. Lydston, in _The Diseases
of Society_, says:
The old adage, _mens sana in corpore sano_, is too often forgotten.
Especially is it ignored by the legislator and penologist. A normal
psychic balance and a brain fed with blood that is insufficient in
quantity or vicious in quality are physiologic incompatibles. The nearer
we get to the marrow of criminality, the more closely it approximates
pathology.
That is to say that the sound mind depends largely on the sound body;
that a brain fed with diseased blood, or with too little blood, cannot
work healthily and well; and that the more we know of crime the closer
do we find its relation to disease.