e in a given case to
account accurately for all the single forces at work. Neither an
outside observer nor the Subject who undergoes the process can explain
fully how particular experiences are able to change one's centre of
energy so decisively, or why they so often have to bide their hour to
do so. We have a thought, or we perform an act, repeatedly, but on a
certain day the real meaning of the thought peals through us for the
first time, or the act has suddenly turned into a moral impossibility.
All we know is that there are dead feelings, dead ideas, and cold
beliefs, and there are hot and live ones; and when one grows hot and
alive within us, everything has to re-crystallize about it. We may say
that the heat and liveliness mean only the "motor efficacy," long
deferred but now operative, of the idea; but such talk itself is only
circumlocution, for whence the sudden motor efficacy? And our
explanations then get so vague and general that one realizes all the
more the intense individuality of the whole phenomenon.

In the end we fall back on the hackneyed symbolism of a mechanical
equilibrium. A mind is a system of ideas, each with the excitement it
arouses, and with tendencies impulsive and inhibitive, which mutually
check or reinforce one another. The collection of ideas alters by
subtraction or by addition in the course of experience, and the
tendencies alter as the organism gets more aged. A mental system may
be undermined or weakened by this interstitial alteration just as a
building is, and yet for a time keep upright by dead habit. But a new
perception, a sudden emotional shock, or an occasion which lays bare
the organic alteration, will make the whole fabric fall together; and
then the centre of gravity sinks into an attitude more stable, for the
new ideas that reach the centre in the rearrangement seem now to be
locked there, and the new structure remains permanent.

Formed associations of ideas and habits are usually factors of
retardation in such changes of equilibrium. New information, however
acquired, plays an accelerating part in the changes; and the slow
mutation of our instincts and propensities, under the "unimaginable
touch of time" has an enormous influence. Moreover, all these
influences may work subconsciously or half unconsciously.[99] And when
you get a Subject in whom the subconscious life--of which I must speak
more fully soon--is largely developed, and in whom motives habitually