219. But let application of this be made to living conatus, and to living force, and to living motion. Living conatus in man, who is a living subject, is his will united to his understanding; living forces in man are the interior constituents of his body, in all of which there are motor fibers interlacing in various ways; and living motion in man is action, which is produced through these forces by the will united to the understanding. For the interior things pertaining to the will and understanding make the first degree; the interior things pertaining to the body make the second degree; and the whole body, which is the complex of these, makes the third degree. That the interior things pertaining to the mind have no power except through forces in the body, also that forces have no power except through the action of the body itself, is well known. These three do not act by what is continuous, but by what is discrete; and to act by what is discrete is to act by correspondences. The interiors of the mind correspond to the interiors of the body, and the interiors of the body correspond to the exteriors, through which actions come forth; consequently the two prior degrees have power through the exteriors of the body. It may seem as if conatus and forces in man have some power even when there is no action, as in sleep and in states of rest, but still at such times the determinations of conatus and forces are directed into the general motor organs of the body, which are the heart and the lungs; but when their action ceases the forces also cease, and, with the forces, the conatus.