Page:The System of Nature.djvu/150

 in their action to the physical laws of attraction and repulsion.

The faculty of perceiving or of being modified, as well by itself as exterior objects which the brain enjoys is sometimes designated by the term understanding. To the assemblage of the various faculties of which this interior organ is susceptible, is applied the name of intelligence. To a determined mode in which the brain exercises the faculties peculiar to itself, is given the appellation of reason. The dispositions or the modifications of the brain, some of them constant, others transitory, which give impulse to the beings of the human species, causing them to act, are styled wit, wisdom, goodness, prudence, virtue, &amp;c.

In short, as there will be an opportunity presently to prove, all the intellectual faculties&mdash;that is to say, all the modes of action attributed to the soul, may be reduced to the modifications, to the qualities, to the modes of existence, to the changes produced by the motion of the brain; which is visibly in man the seat of feeling, the principle of all his actions. These modifications are to be attributed to the objects that strike on his senses; of which the impression is transmitted to the brain, or rather to the ideas, which the perceptions caused by the action of these objects on his senses have there generated, and which it has the faculty to re-produce. This brain moves itself in its turn, re-acts upon itself, gives play to the organs, which concentrate themselves in it, or which are rather nothing more than an extension of its own peculiar substance. It is thus the concealed motion of the interior organ, renders itself sensible by outward