and some of its parts, under pressure of the others, must have got tied up
into knots, like the mainspring of a watch, in such a violent and unhappy
manner that when the pressure is relaxed they fly open as fast as they
can, and unravel themselves with a vast sense of relief. Hence the longing
to satisfy latent passions, with the fugitive pleasure in doing so. But
the external agencies that originally wound up that mainspring never
cease to operate; every fresh stimulus gives it another turn, until it
snaps, or grows flaccid, or is unhinged. Moreover, from time to time, when
circumstances change, these external agencies may encrust that primary
organ with minor organs attached to it. Every impression, every adventure,
leaves a trace or rather a seed behind it. It produces a further
complication in the structure of the body, a fresh charge, which tends to
repeat the impressed motion in season and out of season. Hence that
perpetual docility or ductility in living substance which enables it to
learn tricks, to remember facts, and (when the seeds of past experiences
marry and cross in the brain) to imagine new experiences, pleasing or
horrible. Every act initiates a new habit and may implant a new instinct.
We see people even late in life carried away by political or religious
contagions or developing strange vices; there would be no peace in old
age, but rather a greater and greater obsession by all sorts of cares,
were it not that time, in exposing us to many adventitious influences,
weakens or discharges our primitive passions; we are less greedy, less
lusty, less hopeful, less generous. But these weakened primitive impulses
are naturally by far the strongest and most deeply rooted in the organism:
so that although an old man may be converted or may take up some hobby,
there is usually something thin in his elderly zeal, compared with the
heartiness of youth; nor is it edifying to see a soul in which the plainer
human passions are extinct becoming a hotbed of chance delusions.

In any case each fresh habit taking root in the organism forms a little