_Will_ is a modification of the brain, by which it is disposed to action, that is to say, to give such an impulse to the organs of the body, as can induce to act in a manner, that will procure for itself what is requisite to modify it in a mode analogous to its own existence, or to enable it to avoid that by which it can be injured. To _will_ is to be disposed to _action_. The exterior objects, or the interior ideas, which give birth to this disposition are called _motives_, because they are the springs or movements which determine it to act, that is to say, which give play to the organs of the body. Thus, _voluntary actions_ are the motion of the body, determined by the modification of the brain. Fruit hanging on a tree, through the agency of the visual organs, modifies the brain in such a manner as to dispose the arm to stretch itself forth to cull it; again, it modifies it in another manner, by which it excites the hand to carry it to the mouth. All the modifications which the interior organ or the brain receives, all the sensations, all the perceptions, all the ideas that are generated by the objects which give impulse to the senses, or which it renews within itself by its own peculiar faculties, are either favourable or prejudicial to man's mode of existence, whether that be transitory or habitual: they dispose the interior organ to action, which it exercises by reason of its own peculiar energy: this action is not, however, the same in all the individuals of the human species, depending much on their respective temperaments. From hence the PASSIONS have their birth: these are more or less violent; they are, however, nothing more than the motion of the will, determined by the objects which give it activity; consequently composed of the analogy or of the discordance which is found between these objects, man's peculiar mode of existence, and the force of his temperament. From this it results, that the passions are modes of existence or modifications of the brain; which either attract or repel those objects by which man is surrounded; that consequently they are submitted 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, &c_.