Page:The System of Nature.djvu/98

 which are simple and visible, others concealed and complicated. His life itself is nothing more than a long series, a succession of necessary and connected motion; which operates perpetual changes in his machine; which has for its principle either causes contained within himself, such as blood, nerves, fibres, flesh, bones; in short, the matter, as well solid as fluid, of which his body is composed — or those exterior causes, which, by acting upon him, modify him diversely; such as the air with which he is encompassed, the aliments by which he is nourished, and all those objects from which he receives any impulse whatever, by the impression they make on his senses.

Man, like all other beings in Nature, tends to his own destruction — he experiences inert force — he gravitates upon himself — he is attracted by objects that are contrary or repugnant to his existence — he seeks after some — he flies, or endeavours to remove himself from others. It is this variety of action, this diversity of modification of which the human being is susceptible, that has been designated under such different names, by such varied nomenclature. It will be necessary, presently, to examine these closely and go more into detail.

However marvellous, however hidden, however secret, however complicated may be the modes of action, which the human frame undergoes, whether interiorly or exteriorly; whatever may be, or appear to be the impulse he either receives or communicates, examined closely, it will be found that all his motion, all his operations, all his changes, all his various states, all his revolutions, are constantly regulated by the same laws, which Nature has