sidered as affecting us with another
kind of surprise, or incongruity, as it differs from the usual train
of our ideas, and forms a new link in this perpetual chain; which, as
it thus differs from the ordinary course of nature, we instantly
examine by the voluntary efforts of intuitive analogy; or by
reasoning, which we attend to; and compare it with the usual
appearances of nature.

These ideas which affect us with surprise, or incongruity, or novelty,
are attended with painful or pleasurable sensation; which we mentioned
before as intermixing with all catenations of animal actions, and
contributing to strengthen their perpetual and energetic production;
and also exciting in some degree the power of volition, which also
intermixes with the links of the chain of animal actions, and
contributes to produce it.

Now by frequent repetition the surprise, incongruity, or novelty
ceases; and, in consequence, the pleasure or pain which accompanied
it, and also the degree of volition which was excited by that
sensation of pain or pleasure; and thus the sensorial power of
sensation and of volition are subducted from the catenation of vital
actions, and they are in consequence produced much weaker, and at
length cease entirely. Whence we learn why contagious matters induce
their effects on the circulation but once; and why, in process of
time, the vital movements are performed with less energy, and at
length cease; whence the debilities of age, and consequent death.

ADDITIONAL NOTES. VIII.

REPRODUCTION.

But Reproduction with ethereal fires
New life rekindles, ere the first expires.
CANTO II. l. 13.

I. The reproduction or generation of living organized bodies, is the
great criterion or characteristic which distinguishes animation from
mechanism. Fluids may circulate in hydraulic machines, or simply move
in them, as mercury in the barometer or thermometer, but the power of
producing an embryon which shall gradually acquire similitude to its
parent, distinguishes artificial from natural organization.

The reproduction of plants and animals appears to be of two kinds,
solitary and sexual; the former occurs in the formation of the buds of
trees, and the bulbs of tulips; which for several successions generate
other buds, and other bulbs, nearly similar to the parent, but
constantly approaching to greater perfection, so as finally to produce
sexual organs, or flowers, and