In this category we must include, for example, hypochondria, a disturbance
shown by undue anxiety concerning one's own physical and mental condition.
This disorder, with the allied fears resulting from the urgent desire to
be always absolutely safe, absolutely well, and absolutely comfortable, is
capable, in extreme cases, of so narrowing the circle of pleasure and of
usefulness that the sufferer might almost as well have organic disease.

Neurasthenia (nervous prostration) has for its immediate exciting cause
some overwork or stress of circumstance, but the sufferer not infrequently
was already so far handicapped by regrets for the past, doubts for the
present, and anxieties for the future, by attention to minute details
and by unwillingness to delegate responsibilities to others, that he was
exhausted by his own mental travail before commencing upon the overwork
which precipitated his breakdown. In such cases the occasion of the
collapse may have been his work, but the underlying cause was deeper. Many
neurasthenics who think they are "all run down" are really "all wound up."
They carry their stress with them.

Among the serious results of faulty mental habit must be included also
the doubting folly (_folie du doute_). The victim of this disorder is so
querulously anxious to make no mistake that he is forever returning to see
if he has turned out the gas, locked the door, and the like; in extreme
cases he finally doubts the actuality of his own sensations, and so far
succumbs to chronic indecision as seriously to handicap his efforts. This
condition has been aptly termed a "spasm of the attention."

The apprehensive and fretful may show, in varying degree, signs of either
or all these conditions, according as circumstances may direct their
attention.