The body of the structure is proportioned to the height of the pillars. It contains such parts as are necessary for life, and which consequently ought to be placed in the centre, and shut up in the securest place. Therefore two rows of ribs pretty close to one another, that come out of the backbone, as the branches of a tree do from its trunk, form a kind of hoop, to hide and shelter those noble and tender parts. But because the ribs could not entirely shut up that centre of the human body, without hindering the dilatation of the stomach and of the entrails, they form that hoop but to a certain place, below which they leave an empty space, that the inside may freely distend and stretch, both for respiration and feeding.
As for the backbone, all the works of man afford nothing so artfully and curiously wrought. It would be too stiff, and too frangible or brittle, if it were made of one single bone: and in such a case man could never bend or stoop. The author of this machine has prevented 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 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