that inconveniency by forming vertebrae, which jointing one with
another make up a whole, consisting of several pieces of bones, more
strong than if it were of a single piece. This compound being
sometimes supple and pliant, and sometimes stiff, stands either
upright, or bends, in a moment, as a man pleases. 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