These inequalities alone determine the breadth or narrowness of the forehead, whilst its degrees of inclination depend solely upon the bone which forms it. It is in this way that the hair contributes a little to the expression of the face; I say a little, for it is less to the breadth of the forehead than to its approximation to a perpendicular, that we attach the ideas of majesty and greatness which characterize heroes and gods. The poets, as we know, have particularly celebrated the forehead of the god of thunder. Observe in relation to this subject that there is a great difference between that which expresses majesty or abjectness in the face, from that which serves there to express the passions. It is the osseous structure of this region and the degree of inclination resulting from this structure, which serve for the first use, and it is especially the muscular motions which contribute to the second. Why? Because majesty, grandeur, &c. are especially connected with the extent of the understanding, and the understanding has its seat in the brain, and because the various capacities of the cranium, which contain this organ, and which correspond with its various degrees of development, have inevitably an influence upon the different dimensions of the face. Now as the bony structure is a thing constant and invariable, the air of majesty or abjectness remains always imprinted upon the face. On the contrary, the passions which especially affect the epigastric organs, which afterwards excite the facial muscles, have necessarily a transitory expression. The number of hairs is very variable on the same surface. In some people they are very close together and even all touch; in others more thinly scattered, they allow in part the skin of the cranium to be seen in their interstices, a circumstance which is either owing to original conformation, or to a disease which makes them fall out in part. They have, like the nails, a determinate growth which they do not exceed. We know but little of the limit of this growth. Yet we have seen them reach to the waist, the thighs, and the legs even. It appears that in women they have a greater growth; we might say, that nature has compensated this sex in this way for the want of hair in many other parts. Floating upon the shoulders, the breast, the trunk, &c. they form in the natural state a sort of protection from the injuries of the air and the light. Their extent evidently proves that man was destined to an erect attitude. In fact, in the attitude of quadrupeds, they would trail much upon the earth, and form an obstacle to motion. The hair of no animal, I believe, in a natural attitude retards his progress so much, as the hair of man then would.