430 ON GENERATION. 



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 



