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 things which interiorly constitute his body, in all of which there are motor fibres entwined 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 which belong to the will and the understanding make the first degree. The interior things belonging to the body make the second. And the whole body which is the complex of these makes the third degree. It is well known that the interior things belonging to the mind have no power except through forces in the body, and that forces have no power except through the action of the body itself. 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 interior things of the mind correspond to the interior things of the body; and the interior things of the body correspond to its exterior things by which actions come forth. Wherefore the two prior degrees have power through the exterior things of the body. It may seem as if conatus and forces in man have some power even although there is no action, as in sleep and in states of rest, but at such times, the determinations of conatus and forces are into the general motor organs of the body which are the heart and the lungs. But when the action of these ceases, the forces also cease, and, with the forces, the conatus.