sensation, where the violent exertions, which disabled them, were in
consequence of too great quantity of sensation. And lastly the fibres,
which become disobedient to volition, are probably disabled by their too
violent exertions in consequence of too great a quantity of volition.

After every exertion of our fibres a temporary paralysis succeeds, whence
the intervals of all muscular contractions, as mentioned in No. 3 and 4 of
this Section; the immediate cause of these more permanent kinds of
paralysis is probably owing in the same manner to the too great exhaustion
of the spirit of animation in the affected part; so that a stronger
stimulus is required, or one of a different kind from that, which
occasioned those too violent contractions, to again excite the affected
organ into activity; and if a stronger stimulus could be applied, it must
again induce paralysis.

For these powerful stimuli excite pain at the same time, that they produce
irritation; and this pain not only excites fibrous motions by its stimulus,
but it also produces volition; and thus all these stimuli acting at the
same time, and sometimes with the addition of their associations, produce
so great exertion as to expend the whole of the sensorial power in the
affected fibres.

V. _Of Stimulus less than natural._

1. A quantity of stimulus less than natural, producing a decreased exertion
of sensorial power, occasions an accumulation of the general quantity of
it. This circumstance is observable in the hemiplagia, in which the
patients are perpetually moving the muscles, which are unaffected. On this
account we awake with greater vigour after sleep, because during so many
hours, the great usual expenditure of sensorial power in the performance of