sion of forms. Theirs suffers an arrest, in some instances at a lower, in some at a higher point, but his passes onward to completion.

But that is not all. The biography of the earth, the life of the entire globe, corresponds to this It occurs progress of the individual, to this orderly again in the relation of the animal series. Commencing entire life of the globe. with the oldest rocks that furnish animal remains, and advancing to the most recent, we recognize a continual improvement in construction, indicated by the degree of advancement of the nervous system. The earliest fishes did not proceed beyond that condition of the spinal column which is to be considered as embryonic. The Silurian and Devonian rocks do not present it in an ossified state. Fishes, up to the Carboniferous epoch, had a heterocercal tail, just as the embryos of osseous fishes of the present time have up to a certain period of their life. There was, therefore, an arrest in the old extinct forms, and an advance to a higher point in the more modern. The buckler-headed fishes of the Devonian rocks had their respiratory organs and much of their digestive apparatus in the head, and showed an approximation to the tadpoles or embryos of the frog. The crocodiles of the oolite had biconcave vertebræ, like the embryos of the recent ones which have gained the capability of making an advance to a higher point. In the geological order, reptiles make their appearance next after fishes, and this is what we should expect on the principle of an ascending nervous development. Not until long after come birds, later in date and higher in nervous advancement, capable not only of instinct, but also of intelligence. Of mammals, the first that appear are what we should have expected-the marsupials; but among the tertiary rocks, very many other forms are presented, the earlier ones, whether herbivorous or carnivorous, having a closer correspondence to the archetype than the existing ones, save in their embryonic states, the analogies occurring in Absolute such minor details as the possession of forty- necessity of four teeth. The biography of the earth is thus, transmutaon the great scale, typical of individual life, tion of forms. even that of man, and the succession of species in the

admitting

progress of numberless ages is the counterpart of the transmutation of an individual from form to form. As in a dissolving view, new objects emerge from old ones, and new forms spontaneously appear without the exercise of any periodical creative act.

For some days after birth the

Life of man

accordance

atomy.

actions of the human being are merely reflex. Its cranio-spinal axis from infancy alone is in operation, and thus far it is only an to maturity in automaton. But soon the impressions of exwith his an- ternal objects begin to be registered or preserved in the sensory ganglia, and the evidences of memory appear. The first token of this is perhaps the display of an attachment to persons, not through any intelligent recognition of relationship, but merely because of familiarity. This is followed by the manifestation of a liking to accustomed places and a dread of strange ones. At this stage the infant is leading an instinctive life, and has made no greater advance than many of the lower mammals; but they linger here, while he proceeds onward. He soon shows high powers of memory, the exercise of reason in the determinations of judgment, and in the adaptation of varied means to varied ends.

Such is therefore the process of development of the nervous system of man; such are the powers which consequently he successively displays. His reason at last is paramount. No longer are his actions exclusively prompted by sensations; they are determined much more by ideas that have resulted from his former experiences. While animals which approach him most closely in construction require an external stimulus to commence a train of thought, he can direct his mental operations, and in this respect is parted from them by a vast interval. The states through which he has passed are the automatic, the instinctive, the intellectual; each has its own apparatus, and all at last work harmoniously together. But besides this superposition of an instinctive apparatus upon an automatic one, and an intellectual upon an instinctive, the nervous system consists of two equal and symmetrical lateral portions, individuals. a right half and a left. Each person may be considered as consisting in reality of two individuals.

Every person consists of two lateral

struction.

The right half may be stricken with palsy, the left be unimpaired; one may lose its sight or hearing, the other may retain them. These lateral halves lead independent lives. Yet, though independent in this sense, they are closely connected in another. The brain of the right side rules over the left half of the body, that of the left side rules over the right of the body. On the relationships and antagonisms of the two halves of the cerebro-spinal system must be founded our explanations of the Consequences otherwise mysterious phenomena of double and of this doublealternate life; of the sentiment of pre-existence; ness of conof trains of thought, often double, but never triple; of the wilful delusions of castle-building, in which one hemisphere of the brain listens to the romance suggestions of the other, though both well know that the subject they are entertaining themselves with is a mere fiction. The strength and precision of mental operations depend as much upon the complete equivalency of the two lateral halves as upon their absolute development. It is scarcely to be expected that great intellectual indications will be given by him, one of whose cerebral hemispheres is unequal to the other. But for the detailed consideration of these topics I may refer the reader to my work on Physiology. He will there find the explanation of the nature of registering ganglia; the physical theory of memory; the causes of our variable psychical powers at different times; the description of the ear as the organ of time; the eye as the organ of space; the touch as that of pressures and temperatures; the smell and taste as those for the chemical determination of gases and liquids.

tomical facts.

From a consideration of the construction, development, and action of the nervous system of man, we Conclusions may gain correct views of his relations to other from the foreorganic beings, and obtain true psychical and going anametaphysical theories. There is not that homogeneousness in his intellectual structure which writers on those topics so long supposed. It is a triple mechanism. A gentle, a gradual, a definite development Man a memreaches its maximum in him without a breach ber of the aniof continuity. Parts which, because of their mal series. completion, are capable of yielding in him such splendid

results, are seen in a rudimentary and useless condition in organisms very far down below. On the clear recognition of this rudimentary, this useless state, very much depends. It indicates the master-fact of psychology-the fact that Averroes overlooked-that, while man agrees with inferior beings in the type of his construction, and passes in his development through transformations analogous to theirs, he differs from them all in this, that he alone possesses an accountable, an immortal soul. It is true that there are some which closely approach him in structure, but the existence of structure by no means implies the exercise of functions. In the still-born infant, the mechanism for respiration, the lungs, is completed; but the air may never enter, and the intention for which they were formed never be carried out.

His life and that of the planet alike.

Moreover, it appears that the order of development in the life of individual man and the order of development in the life of the earth are the same, their common features indicating a common plan. The one is the movement of a few hours, the other of myriads of ages. This sameness of manner in their progression points out their dependence on a law immutable and universal. The successive appearance of the animal series in the endless course of time has not, therefore, been accidental, but as predetermined and as certain as the successive forms of the individual. latter we do not find any cause of surprise in the assumption of states ever increasing in improvement, ever rising higher and higher toward the perfection destined to be attained. We look upon it as the course of nature. Why, then, should we consider the extinctions and creations of the former as offering any thing unaccountable, as connected with a sudden creative fiat or with an arbitrary sentence of destruction?

Progress of

humanity is according to

In the

In this book I have endeavoured to investigate the progress of humanity, and found that it shows all the phases of individual movement, the evidence employed being historical, and, therefore, of a nature altogether different from that on which our conclusions in the collateral instances rest. It may serve to assure us that the ideas here presented are

law.

true when we encounter, at the close of our investigation, this harmony between the life of the individual, the life of society, and the life of the earth.

Is it probable that the individual proceeds in his movement of development under law, that the planet also proceeds in its movements under law, but that society does not proceed under law?

Man, thus, is the last term of an innumerable series of organisms, which, under the domination of law, Eternity and has, in the lapse of time, been evolving. Law universality has controlled the inorganic world, and caused of that law. the earth to pass through various physical conditions, gently and continuously succeeding one another. The plastic forms of organic beings have been modelled to suit those changing conditions. The invariability of that law is indicated by the numberless ages through which it has been maintained, its universality by its holding good in the life of the meanest individual.

But it is only a part of sociology that we have considered, and of which we have investigated the development. In the most philosophical aspect the subject in- Comparative cludes comparative as well as human sociology, sociology. For, though there may not be society where actions are simply reflex, there is a possibility of it where they are instinctive, as well as where they are intellectual. Its essential condition being intercommunication, there are necessarily modifications depending respectively on touch or upon the higher and more delicate senses. That is none the less society which, among insects, depends upon antennal contacts. Human society, founded on speech, sight, hearing, has its indistinct beginnings, its rudiments, very low down in the animal scale, as in the bell-like note which some of the nudibranchiate gasteropods emit, or the solitary midnight tapping with which the death-watch salutes his mate. Society resting on instinct is characterized by immobility; it is necessarily unprogressive. Society resting on intellect is always advancing.

But, for the present, declining this general examination of sociology, and limiting our attention strictly to that of humanity, we can not fail to be struck with the fact that in us the direction of evolution is altogether toward