Page:The Works of William Harvey (part 1 of 2).djvu/530

 ingenuity. Among the number : whether the heart gives life and virtue to the blood; or, rather, the blood to the heart. Whether the blood be extant for the sake of the body as mat- ter, nourishment, and instrument; or, on the contrary, the body and its parts are the cause of the blood, and constituted for the sake of the vital principle which especially inheres in it. In like manner, whether the auricles or the ventricles of the heart are the chief, the auricles being the first to live and pulsate, the last to die. Further, whether the left ventricle, which in man is of greater length, and is also surrounded with thicker and more fleshy walls, and is regarded as the source of the spirits, be hotter, more spirituous, excitable, and excellent, than the right, which contains a larger quantity of blood, and is the last to become unstrung by death ; in which the blood of the dying accumulates, congeals, and is deprived of life and spirit; to which, moreover, as to a fountain head, the first um- bilical veins bring their blood, and from which they themselves derive their origin.

So much appears from careful observation of the order ob- served in the production of the parts, and certain other points that follow as deductions from these, and do not a little mili- tate against the commonly received physiological doctrines, viz. : since it is manifest that sensation and motion exist be- fore the brain, all sensation and motion do not proceed from the brain ; from our history it is clearly ascertained that sense and movement inhere in the very first drop of blood produced in the egg, before there is a vestige of the body. The first scaffolding or rudiment of the body, too, which we have said is merely mucilaginous, before any of the extremities are visi- ble, and when the brain is nothing more than a limpid fluid, if lightly pricked, will move obscurely, will contract and twist itself like a worm or caterpillar, so that it is very evidently possessed of sensation.

There are yet other arguments deduced from sense and mo- tion whence we should infer that the brain was not so much the first principle of the body, in the way the medical writers maintain, as the heart, agreeably to Aristotle's view.

The motions and actions which physicians style natural, be- cause they take place involuntarily, and we can neither prevent nor moderate, accelerate nor retard them by our will, and they