into the nostrils, as before explained, and an increase of tears is poured
into the eyes. Any one may observe this, when very young infants are about
to suck; for at those early periods of life, the sensation affects the
organ of smell, much more powerfully, than after the repeated habits of
smelling has inured it to odours of common strength: and in our adult
years, the stronger smells, though they are at the same time agreeable to
us, as of volatile spirits, continue to produce an increased secretion of
tears.

This pleasing sensation of smell is followed by the early affection of the
infant to the mother that suckles it, and hence the tender feelings of
gratitude and love, as well as of hopeless grief, are ever after joined
with the titillation of the extremity of the lacrymal ducts, and a
profusion of tears.

Nor is it singular, that the lacrymal sack should be influenced by pleasing
ideas, as the sight of agreeable food produces the same effect on the
salivary glands. Ac dum vidimus insomniis lascivæ puellæ simulacrum
tenditur penis.

Lambs shake or wriggle their tails, at the time when they first suck, to
get free of the hard excrement, which had been long lodged in their bowels.
Hence this becomes afterwards a mark of pleasure in them, and in dogs, and
other tailed animals. But cats gently extend and contract their paws when
they are pleased, and purr by drawing in their breath, both which resemble
their manner of sucking, and thus become their language of pleasure, for
these animals having collar-bones use their paws like hands when they suck,
which dogs and sheep do not.

4. _Of Serene Pleasure._