Whilst the acquiring of languages, the making of tools, and the labouring
for money; which are all only the _means_ of procuring pleasure; and the
praying to the Deity, as another _means_ to procure happiness, are
characteristic of human nature.

* * * * *

SECT. XVII.

THE CATENATION OF MOTIONS.

I. 1. _Catenations of animal motion._ 2. _Are produced by irritations,
by sensations, by volitions._ 3. _They continue some time after they
have been excited. Cause of catenation._ 4. _We can then exert our
attention on other objects._ 5. _Many catenations of motions go on
together._ 6. _Some links of the catenations of motions may be left out
without disuniting the chain._ 7. _Interrupted circles of motion
continue confusedly till they come to the part of the circle, where
they were disturbed._ 8. _Weaker catenations are dissevered by
stronger._ 9. _Then new catenations take place._ 10. _Much effort
prevents their reuniting. Impediment of speech._ 11. _Trains more
easily dissevered than circles._ 12. _Sleep destroys volition and
external stimulus._ II. _Instances of various catenations in a young
lady playing on the harpsichord._ III. 1. _What catenations are the
strongest._ 2. _Irritations joined with associations from strongest
connexions. Vital motions._ 3. _New links with increased force, cold
fits of fever produced._ 4. _New links with decreased force. Cold
bath._ 5. _Irritation joined with sensation. Inflammatory fever. Why
children cannot tickle themselves. 6. Volition joined with sensation.
Irritative ideas of sound become sensible._ 7. _Ideas of imagination,