hat a fit
of anger is apt to bring on a headache, but they have not stopped to
look for the reason, or if they have, they have often gotten
themselves into a tangle. This is because there has always been, until
recently, a missing link. Now the link has been found. After the last
chapter, it will not be hard to understand that this connecting link,
this go-between of body and mind, is nothing else than the
subconscious mind. When we remember that it has the double power of
knowing our thoughts and of controlling our bodies, it is not hard to
see how an idea can translate itself into a pain, nor to realize with
new vividness the truth of the statement that healthy mental states
make for health, and unhealthy mental states for illness.

=Suggestion and Emotion.= There are still many gaps in our knowledge
of the ways of the subconscious, but investigation has thrown a good
deal of light on the problem. Two of the principles already discussed
are sufficient to explain most of the phenomena. These are, first,
that the subconscious is amenable to control by suggestion, and
secondly, that it is greatly influenced by emotion. Tracing back the
principles behind any example of the power of mind over body, one
finds at the root of the matter either a suggestion or an emotion, or
both. If, then, the stimulating and depressing effects of mental
states are to be understood, the first Step must be a fuller
understanding of the laws governing suggestion and emotion.

THE CONTAGION OF IDEAS

One of the most important points about the subconscious mind is its
openness to suggestion. It likes to believe what it is told and to act
accordingly. The conscious mind, too,--proud seat of reason though it
may be,--shares this habit of accepting ideas without demanding too
much proof of their truth. Even at his best, man is extremely
susceptible to the contagion of ideas. Most of us are even less immune
to this mental contagion than we are to colds or influenza; for ideas
are catching. They are such subtle, insinuating things that they creep
into our minds without our knowing it at all; and once there, they are
as powerful as most germs.

Let a person faint in a crowded room, and a good per cent. of the
women present will begin to fan themselves. The room has suddenly
become insufferably close. After we have read half a hundred times
that Ivory soap floats, a fair proportion of the population is likely
to be seized with desire for a soap t