is the term we apply to what the brain does beyond maintaining itself and the body
that it controls.Thought, emotion, memory, sensation all result from the constant
dance of nerve impulses within the brain. That dance is dependent upon the condi-
tion of the nerve cells which constitute most of the brain and by the neurotransmit-
ters which shuttle between neighboring cells. Too many dead or dying cells and the
mindlessness of dementia is inescapable. Too little serotonin can drown a person in
the deeps of depression, altering his personality, his appearance, his beliefs about
the world and himself—even changing, literally, the way he sees what is around
him. The manic-depressive harbors no demons and is not "sick" or "diseased" in
the way one usually thinks of illnesses.Rather, he is someone whose brain chem-
istry may at various times differ from the average and at other times may not. From
normalcy, however defined, to psychosis is a continuum, not a series of discrete
categories. No one knows where to draw the line between the well and the ill
because there is no line. Anyone can become manic under the influence of the
appropriate drugs—and anyone can become depressed—again, it is a matter of
chemistry. The manic-depressive is not an alien from outer space, he is one of us.

This third revolution in the Western concept of mind has not been delivered by
philosophers, it has been thrust into our hands by modern technology and science.It
is a child of the laboratory, not the academic's study. And one of the lessons it has
taught is that the mind of man is not as exceptional as once was thought. Descartes
believed that only human beings could think; animals were merely fleshy machines
that responded to stimuli.Recent research shows that chimpanzees can solve prob-
lems, form sentences, even insult their trainers, which does seem to suggest that
thinking is going on. The human nervous system is not all that different from that of
other species, fortunately for us, or much that neurologists have learned from exper-
iments on other animals would be worthless for human purposes.

In summation, the three revolutions in the Western concept of the human mind
have left us with some useful notions.The first revolution established that reason can
tell us a lot about the natural world, including ourselves. Our modern scientific, tech-
nological world is unimaginable without that legacy. The second revolution taught us
that reason must not be overestimated as a cause of human behavior because many
other factors can at any given moment override reason. Otherwise, no one would con-
tinue to smoke tobacco. Our third and ongoing revolution has shown us so far that
what the mind does, and one's mental health in general, are determined by the con-
dition of brain cells and the precise chemical state of the brain. Consequently, the
mentally ill are not a breed apart, and can benefit greatly from appropriate medica-
tion. The above are not very elegant, as ideas go. But it is indisputable that the three
revolutions have transformed our civilization and even the planet we call home.

The book you hold in your hands takes us to the next step in this third revo-
lution, which requires a new look at civilization itself. We can only make a begin-
ning here. But it is time to discover how much civilization has gained from those
whose brain chemistry was not always in the zone of the statistical average—the
manic-depressive geniuses.

-6-