explanation of all known phenomena, including consciousness itself. This struggle for unity was almost inevitable in the first efforts to solve the problem, on account of the nature of the problem itself. For, in its simplest and most comprehensive form it was this, to account for all life. Life embraced all known forms, from human life at the one extreme, to reptile and insect life, and even animalculæ, at the other. And as life is familiar to us in physical forms, or, if that be a better mode of expression, in visible forms, it was easy to regard the whole problem of life as if it involved nothing more than bodily life. Indeed at the outset, there was nothing which required, perhaps nothing present to the scientific inquirer which warranted, an admission of the reality of mental life. There was thus, almost inevitably at the outset, apparent discredit thrown on mental existence, and the whole investigations of mental philosophy. The perplexity of life itself, even in its physical forms, being exceedingly great, investigations of a difficult and complicated kind, bearing closely on the solution of the problem, might be carried on, without its being forced upon the attention of those engaged in them, that there is an additional perplexity involved in the fact of consciousness. As long as the extent and direction of inquiry left this second complication out of view, the whole character of the investigation could not fail to wear the appearance of a denial of mental philosophy. But sooner or later, the inquiry must arise, as to how much is involved in the highest form of known life. As soon indeed as some success seems attained in explaining life in its germ or basis, investigation must be continued in the attempt to apply it upwards to life in forms of organization increasingly complex. If germ forces may explain the life of a worm, a further combination of the same forces may explain the life of a newt; and a further combination, that of a horse. If in prosecuting this theory it be observed that the increasingly complex organization proceeds in analogous types, improving upon what has gone before, a theory of natural development may come to the aid of the germ theory, lending additional probability to the whole. But the course of procedure is leading directly upon the second perplexity--Consciousness. Here the struggle after unity becomes more trying. Muscles, nerve, and brain have all been found already. What we have here is only finer nerve, with larger brain, having more involved convolutions. Shall we not then say that the vital energy in the brain manifests itself in the form of thought, feeling, volition, and other phenomena of consciousness? This is a perfectly legitimate thing to say, as a provisional hypothesis which may give us a clue for further inquiry. But now comes into use the old method of mental philosophy, much as it has been maligned. There is no escape. The dissecting knife

and the forceps can render us no aid here. We must go back to the old plan of questioning consciousness. Accepting the testimony of science as to the existence of the nerves, and of the nerve-centres in the brain, and as to the functions of these, there is still another sphere of knowledge lying open to experience and observation, which requires to be embraced in our inquiry. This is the sphere of consciousness. That within this sphere a distinct class of facts is brought under observation can be clearly shown. What is within consciousness, physiology cannot account for; what belongs to physiology, consciousness cannot account for. This is matter of experience and observation, capable of being tested by any one. The distinction between the nerves of sensation and the motor nerves will suffice for illustration.

First, take an impression made on the tips of the fingers when the nerves of sensation are brought into use. Physiology discovers that the nerves of sensation run up the arm, and terminate in the brain. It is thus shown that there is a contrivance for the transmission of the impression from the tips of the fingers to the nerve-centre, just as pressure on the surface of a wire-spring affects the whole coil behind. Further than this physiological investigations do not carry us. Presumably there is an end to serve by this contrivance. It is not to be supposed that vital energy is expended in the transmission of an impression over an extended surface to a grand centre, if the same end could have been gained by the impression being made only at the extremity. Yet, the man who feels the impression at the tips of the fingers, does not in consequence feel any impression in the brain, any more than he feels an impression in the heel. Passing now into consciousness, however, we find that, in conjunction with the impression at the tips of the fingers, we are conscious of a sensation, affording knowledge as to some of the qualities of the object by contact with which the impression was received. But how consciousness arises cannot be explained, either from the scientific or from the philosophical side. Still, if this were all, we should not be warranted from our ignorance to conclude that this consciousness of sensation belonged to a separate order of facts. The presumption might still be in favour of the hypothesis that vital energy is evolved in the brain in the form of sensation. But now let us reverse the point of observation.

arm.

Take the motor nerves in their relation to the brain, and to any other power which may be known in exercise. I will to move my In this case, action is from within, outwards. The result is at the extremity, and the origin somewhere else. We may take the successive facts either in their natural order, or in the reverse order. If we take the reverse order first, we are in the region of physiology.

But while

There is the movement of the muscles; that is produced by the vital energy in the motor nerves; that energy is transmitted from the brain. But here, as before, physiology comes to a stand-still. How the brain was brought into action in this particular direction, cannot be told, or whether there is anything beyond to account for the action, it is impossible to say. But, if now we turn to consciousness, or perhaps I may simply say to our own experience, we know that there is still another fact, the originating fact, left unnamed and unexplained. Consciousness discovers the volition in which the action of the arm originated. As Professor Huxley has said in another relation, "Our volition counts for something as a condition of the course of events" ("Lay Sermons," p. 159, "Protoplasm "). Volition is in this case known as the beginning of the whole, while I am conscious of the muscular sensation connected with the movement of the arm, as well as of the visible perception of its motion. But consciousness discovers nothing of the action of the brain, and of the motor nerves. Thus, then, it begins to appear that in human life there are facts beyond the range of the physiology of nerve and brain, yet in close connection or correlation with them. the correlation is certain, the mode of relation is undiscovered, and, so far as appears, undiscoverable. There is nerve-action, and some other action in conjunction with it; there is brain-work, and some other form of work behind and above. In so far as these distinct, yet correlated facts, have come into view, as connected with the problem of life, there is an obvious disposition on the part of scientific inquirers to admit the existence of mind, and the high place of mental philosophy, as an agent for dealing with the great problems of existence. This is the noteworthy circumstance at the present time to which I feel anxious that your attention should be directed. The dualism of mind and matter has now begun to receive the testimony of physical science, not only after the adverse appearances connected with theories of protoplasm and development, but as the direct result of the prosecution of these. The struggle towards unity in a theory of all life has been strenuously maintained, until the hopelessness of the attempt has been allowed, by those who have been most earnest and successful in prosecuting the investigations which the character of the problem imposed.

You will not understand me to mean that the struggle after unity has altogether ceased, or that its hopelessness has been admitted with anything approaching unanimity. But, it is specially worthy of notice on the part of those engaged in the study of philosophy, that the broad distinction between nerve-energy and mind-energy has been decidedly maintained by many of the most distinguished promoters of scientific inquiry. The first marked indication of this, to

which I would call attention, was the utterance of Professor Tyndall at the meeting of the British Association at Norwich, in 1868. The following extract will show the position then taken. He says:

"The passage from the physics of the brain to the corresponding facts of consciousness is unthinkable. Granted that a definite thought, and the definite molecular action in the brain occur simultaneously, we do not possess the intellectual organ, nor apparently any rudiment of the organ, which would enable us to pass, by a process of reasoning, from the one phenomenon to the other. They appear together, but we do not know why. Were our minds and senses so expanded, strengthened, and illuminated as to enable us to see and feel the very molecules of the brain; were we capable of following all their motions, all their groupings, and all their electric discharges, if such there be, and were we intimately acquainted with the corresponding states of thought and feeling, we should be as far as ever from the solution of the problem, 'How are these physical processes connected with the facts of consciousness?' The chasm between the two classes of phenomena would still remain intellectually impassable." (Report of British Association for 1868.)

Anything more explicit than this we could not have in testimony to the essential separation of the two classes of facts, to the distinct province of investigation belonging to mental philosophy, and to the old method of philosophising, as the only available method for reaching the facts of mind.

Comparatively few of the special upholders of physical science who were engrossed in study as to a physical basis of life, and the development of species, either would or could have spoken out so decidedly two years ago, when Professor Tyndall uttered the words just quoted. But these two years have been sufficient to bring about a considerable change. It was shortly after the Norwich meeting that Professor Huxley delivered the lecture on Protoplasm, or the physical basis of life, which awakened great interest on many accounts. The somewhat fierce antagonism which it encountered must be still fresh in your memory. Subsequent study, taken in connection with later utterances, has been sufficient to show that first impressions were not altogether just. In fairness, however, it must be admitted that a considerable share of the responsibility rested with the author, as well as with his readers. References to mind were so intermingled with allusions to matter, that the reader's task was unusually critical, especially for those who were willing to accept the theory as applied to physical life, while they demurred to its wider application. If the lecture could have been read in the light of an acceptance of Professor Tyndall's position, one-half of the outburst of antagonism might have been saved. It was not clear that Professor Huxley accepted it, but as little that he rejected it. At some points of the lecture it appeared as if he saw the distinction, and owned it; at other parts it appeared as if he could make no such acknowledgment.

In particular, whenever he became prophetic, his attitude looked threatening towards mental philosophy. Thus he proclaimed that the progress of science" now, more than ever, means the extension of the province of what we call matter and causation, and the concomitant gradual banishment from all regions of human thought of what we call spirit and spontaneity."* Now there are many who anticipate, as the probable fruit of scientific progress, the extension of causation, and banishment of spontaneity, who cannot see in the present position of science any prospect, either of extending the province of matter, or of banishing spirit. And to add to our perplexity, there are later passages in the lecture which make it at least doubtful whether Professor Huxley himself expects the banishment of spirit. Indeed, but for the traces of some degree of inconsistency, as in the quotation just given, I should say he has made it pretty plain that he really anticipates no such thing. When, still in the prophetic vein, he adds, " As surely as every future grows out of past and present, so will the physiology of the future gradually extend the realm of matter and law, until it is co-extensive with knowledge, with feeling, and with action;" + the language is much more guarded, if it does not actually point in the very opposite direction. "Coextensive " carries a very different meaning from "banishment.” A man's clothes may be co-extensive with his body; a plantation of trees may be co-extensive with an enclosure of ten acres of ground; but the clothes are not the body, and the plantation is not the field. So if physiology anticipates the time when it shall be co-extensive with knowledge, feeling, and action, nothing is anticipated adverse to the admission of the separate existence of mind, but quite the contrary. Accordingly, in this same lecture, we find the strongest condemnation of the materialistic theory, implying the impossibility of reducing all known life to unity in a physical basis. He says, "The materialistic position that there is nothing in the world but matter, force, and necessity, is as utterly devoid of justification as the most baseless of theological dogmas." And again, "The errors of systematic materialism may paralyse the energies, and destroy the beauty of a life."§ Anything more thoroughly in harmony with the uniform testimony of mental philosophy, we could not have.

With such extracts to guide towards a judgment, it seems to me that a general summary of the result of the lecture on Plotoplasm as bearing on Mental Philosophy, may be briefly stated thus: Professor Huxley clearly proclaims that the whole problem of life is embraced in human life, as the highest known to us; and his direct references to mind, while not always consistent, are guarded, and such as to indicate a wish, for the time, to avoid definite and

"Lay Sermons," p. 156. † Ibid., p. 156. + Ibid., p. 158. § Ibid., p. 160-1.