This successive and gradual order of development, the stationary state, and the decay of the brain, constitute the cause, and serve to explain why, in the new born child, the only functions are those of the senses, of voluntary movement, the expression of the want of nourishment, and confused sentiments of pleasure and of pain, of desire and of aversion; why all this takes place in an imperfect degree only; why the child begins by degrees to pay attention to exterior things, to act upon them, and to manifest fixed desires and propensities; how impressions are preserved, and how these impressions become ideas and notions; how the faculties and the qualities begin to act, and to manifest themselves under the semblance of different talents, as well as of various propensities, for example of love, of friendship, of vanity, of ambition, of pride, &c.; how the child becomes successively adolescent, a young man, a matured man; how, from this epoch, all the moral and intellectual powers of the man have acquired their greatest energy, until the moment when they begin to decrease, and to lose insensibly more or less of their duration and of their activity; finally how, in old men, blunted sensations and debility of mind, alone remain. By this succession and development it may be clearly seen that the faculties of the mind and their manifestation follow, step by step, the state of their material conditions. The progress of the functions is the same as that of the organs. Nothing, then, could more evidently show that the manifestation of these faculties depend on the organization.

2nd. When the development of the organs of the moral qualities and of the intellectual faculties, does not follow the accustomed gradual order, the manifestation of the functions of these organs deviates also from its usual order?

It is frequently observed in rachitis, that the intellectual faculties of children are more active than is suitable to their age. The reason of this is, that a common effect of this malady is to give to the brain an extraordinary development

and irritability. Sometimes even a single part of the brain developes itself too early, without the existence of any malady; and in this case, the function peculiar to this part never fails of manifesting itself at the same time. We have, for example, observed several children in whom the part of the brain, which relates to physical love, had acquired an extraordinary development at the ages of three and four years. These children were overpowered by this unhappy propensity although their sexual parts, even when they experienced some agitation, had rarely acquired an analogous development. Other children, in whom the same organization has been remarked, manifested the phenomena of complete virility, while the other faculties were yet undeveloped. I shall, moreover, cite several similar facts, relative to the organs of each faculty. Is it that the different parts of the brain acquire or that the entire brain acquires maturity and solidity at a late period? Then the state of childhood and of demi-imbecility are prolonged until the age of ten to twelve years. But at this period nature seems to operate with new energy, in the development of the parts: children, in whom, until this period, we had expected no talent, become sometimes, in a short time, individuals of great talent. Gessner, one of the best and most amiable poets of Switzerland, experienced this. Born in a family to which rickets is habitual in youth, his teachers, when he had attained the age of ten years, declared him entirely incapable of making any progress. One of the most celebrated doctors of Berlin, was not, up to his thirteenth year, able either to combine ideas, or to make use of the organs of language.

The simultaneousness of the manifestation of the functions and of the irregular development of the organs, whether precocious or tardy, is then a constant phenomena which cannot be questioned: and it necessarily results from this phenomena, that the exercise of the qualities of the mind depends on material organs.

3rd.-If the development and perfecting of the cerebral organs have not been completed, the manifestations of the respective qualities and faculties remain equally incomplete?

Although the energy of the functions of the organs depends not on their development alone, but also on their excitability, the degree of development of the brain, necessary to its functions, can be determined with certainty. The observations of all times have established, that the brain is incapable of fulfilling its destination, when its bony covering, or the cranium, is but thirteen to seventeen inches in circumference, by measure from the most arched part of the occiput, passing over the temples, and over the most elevated part of the forehead.

Willis has described the brain of a young man, imbecile from his birth; its volume is scarcely the fifth part of that of an ordinary human brain. I have had a copy taken of it, according to Willis, in my great work. M. Bonn, Professor at Amsterdam, possesses two small skulls of idiots, and the brain of an imbecile person, who lived to the age of twentyfive years. He was so stupid, that, although he was born at Amsterdam, they passed him off for a wild man of Africa, and exhibited him for money. M. Pinel has a similar skull of a young girl, of eleven years of age, completely idiotic. Among the anatomical preparations of the school of medicine at Paris, there is also a skull undeveloped, of an imbecile child. I have had two similar skulls drawn, out of my collection, both distinguished by their diminutive size; the first 3 is the skull of a child of seven years of age; the other 1 that of a girl of twenty years of age: these two individuals were completely imbecile. I have observed heads equally small in several persons, imbecile from birth, still living. All these skulls, and all these heads, are thirteen or fourteen inches in circumference, and eleven or twelve inches from the root of

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the nose to the great occipital hollow. If sometimes dwarfs, who, to a certain extent, possess intellectual faculties, appear to form an exception to this law, the size of their head has not been observed with exactitude, and it is, in these cases, always very disproportioned to the rest of the body-even when heads are a little larger than those which characterize complete imbecility, the intellectual faculties are however almost entirely inactive.

In proportion as, in the various degrees which characterize imbecility, the organization of the brain is perfected, the faculties manifest themselves in the same proportion. The individuals, who are in this degree of development, manifest some particular dispositions and propensities; their gestures become more significant; they even go so far as to produce short and well connected phrases. Thus the functions are elevated with the organization, until weakness of the mind is no longer detected except in a few points, or in one point only.

Hence it is seen, that not all the individuals, who are reputed imbecile, are completely so. Parents and medical men sometimes find it difficult to understand how a child that acquits itself well of all that is required of it in a house, and who manifests accurate sensations, sensibility, and even artifice, can be classed with idiots. Such is, however, the state of some children who hear, but do not learn to speak. I have given attention to this point, in considering the sense of hearing;1 and when I treat of the articulated language particular to man, I shall show that this accident has for its cause an organic malady of the brain, and hence arises the want of power of exercising all its functions.

At Hamburgh, we saw a young man of sixteen years of age, the anterior inferior parts of the head of whom were well developed; but his forehead was scarcely an inch high, because the anterior superior parts of the brain had been cramped in their development; and he, consequently, enjoyed the exercise of the functions appropriated to the anterior

1 Anatomie et Physiologie du cerveau, T. i., S. vi.

inferior parts only: he learned names, numbers, epochs, history, and he repeated all these mechanically; but combination, the comparison of ideas, and judgment, failed him entirely. He was rightly regarded as imbecile, and could not be employed for anything. I shall have occasion in the course of subsequent essays, to cite several examples which confirm the proposition, that the defective development of the brain, and of particular organs, has always for result, the weakness of their action.

4th.-When the organs of the mind have acquired a high degree of development and of perfection, the result is, a possibility in these organs of manifesting their functions with much energy.

I shall prove the truth of this result, when I treat of the influence of the development of the organs, and upon the exercise of their corresponding organs. I shall at the same time show, that, when individuals distinguish themselves particularly and in a remarkable manner by a fixed quality, oṛ indeed when they are influenced by a fixed idea, or propensity, a partial mania, monomania, by a too great excitement, it is almost always the extraordinary development of some organ which causes the same. Without entering now into these details, I shall content myself with drawing attention to the manifest difference, which every one may remark, in three kinds of heads, viz. :-the heads of idiots, the heads of men the talents of whom are but mediocre, and the heads of eminent men gifted with vast and great genius. The first are characterized by their diminutiveness, as we have just seen, and the last by their large size. The heads of idiots are characterized, unless the brain be in any other respect diseased, either by a deformity, or by their diminutiveness; the heads of men possessing eminent qualities are distinguished by their extent.

This nice difference is made evident in the productions of the fine arts. We see that artists in their works, conformably to the indications of nature, give large heads, and above all large foreheads to energetic persons, endowed with intel