leases. All these
vertebrae have in the middle a gutter or channel, that serves to
convey a continuation of the substance of the brain to the
extremities of the body, and with speed to send thither spirits
through that pipe.

But who can forbear admiring the nature of the bones? They are very
hard; and we see that even the corruption of all the rest of the
body, after death, does not affect them. Nevertheless, they are
full of numberless holes and cavities that make them lighter; and in
the middle they are full of the marrow, or pith, that is to nourish
them. They are bored exactly in those places through which the
ligaments that knit them are to pass. Moreover, their extremities
are bigger than the middle, and form, as it were, two semicircular
heads, to make one bone turn more easily with another, that so the
whole may fold and bend without trouble.

SECT. XXXV. Of the Organs.

Within the enclosure of the ribs are placed in order all the great
organs such as serve to make a man breathe; such as digest the
aliments; and such as make new blood. Respiration, or breathing, is
necessary to temper inward heat, occasioned by the boiling of the
blood, and by the impetuous course of the spirits. The air is a
kind of food that nourishes the animal, and by means of which he
renews himself every moment of his life. Nor is digestion less
necessary to prepare sensible aliments towards their being changed
into blood, which is a liquor apt to penetrate everywhere, and to
thicken into flesh in the extreme parts, in order to repair in all
the members what they lose continually both by transpiration and the
waste of spirits. The lungs are like great covers, which being
spongy, easily dilate and contract themselves, and as they
incessantly take in and blow out a great deal of air, they form a
kind of bellows that are in perpetual motion. The stomach has a
dissolvent that causes hunger, and puts man in mind of his want of
food. That dissolvent, which stimulates and pricks the stomach,
does, by that very uneasiness, prepare for it a very lively
pleasure, when its craving is satisfied by the aliments. Then man,
with delight, fills his belly with strange matter, which would
create horror in him if he could see it as soon as it has entered
his stomach, and which even displeases him, when he sees it being
already satisfied. The stomach is made in the figure of a bagpipe.
There the aliments being dissolved by a quick coc