Undoubtedly the inclination of the pelvis in the fœtus, the disposition of the femora, and the want of curvature in the spine, adapt it but little for standing immediately after birth; but with these causes is certainly also combined the want of exercise.[45] Who does not know, that if a limb be suffered to remain immoveable for a length of time, it loses the habit of moving, and that when afterwards its service is required, it requires a new kind of education before it can exercise its movements with any regularity or precision. The man, who for a long time should condemn himself to silence, would experience in like manner the same embarrassment in his first attempt at utterance. From these considerations we may conclude that our exterior life, to allow myself the expression, is learnt, and requires before it can be perfected, a sort of apprenticeship. IV. _Of the influence of society over the education of the organs of the animal life._ Over this sort of education, which the organs of the animal life receive, society exercises a very great influence; it enlarges the sphere of action of some of them, lessens it for others, and modifies it in them all. I shall first remark, that it constantly gives to some of the organs a perfection greater than naturally should be their portion. Such in fact is the nature of our occupations as always to require the especial action of some one, or other of these organs. The ear of the musician, the palate of the cook, the brain of the philosopher, the muscles of the dancer, and the larynx of the singer, receive in addition to the general education of the exterior life, a particular education. Under these considerations, the occupations of mankind might be divided into three classes. The first would comprehend all those, which especially regard the senses, such as painting, music, and sculpture, the acts of the perfumer and the cook, and in a word all those the results of which are productive of pleasure to the senses. In the second would be ranged the occupations, wherein the brain is chiefly called into action; such as poetry, the sciences of nomenclature, the mathematics and metaphysics. The occupations of dancing, equitation, and the mechanic acts would form the third class.[46] Each several occupation then of the individual, brings into permanent activity, some one organ in particular, and gives it a peculiar perfection. The ear of the musician in a piece of harmony, and the eye of the painter in a picture, distinguish many things which entirely escape the vulgar. It frequently happens that this perfection of action, is accompanied in the more exercised organ with an excess of nutrition: this we may frequently observe in the muscles of the arm of the baker, in those of the inferior limbs of the dancer, and in those of the countenance of the player.