to another substance it does not know-matter-without being able to reconcile them, as is natural, for how can light be produced out of the clash of two ignorances? On the contrary, the partisan of experience pronounces the question unsolvable, precisely because it transcends experience, that is to say, demonstrated or verifiable science. The one is pent within the impotency of his metaphysics; the other within the limits of his method. The ignorance of the former is owing to the gaps in his philosophy; that of the latter, to his voluntary abstention from all transcendental research.

In our times, the fine generalization known as the law of equivalence, or of the correlation of forces, has led some bold thinkers to state in another form the problem of the relations between the physical and the moral. Modern physics considers all the forces of nature-heat, light, electricity, magnetism, cohesion, chemical affinity, gravity—as capable of being reduced all to one principle, and of being transformed into one another in accordance with fixed rules, which are nothing else but the laws of mechanics. It is also generally admitted that the law of equivalence governs vital phenomena, and muscular contraction and innervation in particular. But is it also applicable to mental phenomena ? Is it possible for it to pass from nerve facts to states of consciousness ? Do mental forces enter the category of the other forces, and are they in like manner convertible?

Some authors in our day answer affirmatively. Bain has accumulated and cited some facts from which he infers, (1) the equivavalence or transmutability of nervous and mental forces, and (2) the equivalence or transformation of the mental forces into one another. Thus, according to him, it would be possible to establish an equivalence on the one hand between a certain nervous state and a certain mental state, and on the other hand between the three principal forms of mental life-sensibility, will and intelligence; so that a state of consciousness would imply the transformation and expenditure of a certain amount of nerve-force; and an increase of sensibility would be possible only by a diminution of intelligence and will, the sum of force in the living being remaining constant amid all these transformations. The magnificent synthesis contained in Herbert Spencer's First Principles reduces all phenomena without exception to the law of equivalence.

'No thought, no feeling,' says the author, 'is ever manifested, save as the result of a physical force. This principle will before long be a scientific common place.'

They who hold this doctrine observe that nervous force, which ultimately results from nutrition, must, after it is produced, be expended in one or other of these three ways: either by acting on the viscera, the heart, or the digestive organs, as is the case in deep emotion; or by acting on the muscles and producing movements, gestures, and various expressions of the physiognomy; or by causing the excitation to pass to some other part of the nervous system, and hence result those successive states which make up consciousness. Sensations excite ideas and emotions; the latter in turn awaken other ideas and emotions, and so on—that is to say, the tension existing in certain nerves, or groups of nerves, when they give us sensations, ideas, or emotions, produces an equivalent tension in some other nerves, or groups of nerves, with which they are connected.

But the facts cited in support of this thesis do not appear to us to be all equally conclusive. Some of them are no doubt transformations, but then others are rather correspondences. Thus, the pain which is transformed into cries and extravagant contortions is of short duration; pain which endures is reticent of expression. And the same is to be said of anger. But in certain cases-for example, in the cerebral excitation produced by hasheesh or opium —it is not quite certain that between the nervous state and the mental state there exists equivalence, transformation, and not simply correspondence.

This doctrine of the correlation of physical forces and thought is as yet hardly more than an outline. It is still in the qualitative period, and it is doubtful whether it will very soon enter on the quantitative period, which alone can constitute it a science. It is however a promising field, and one well adapted to exercise free and daring minds. If it could be demonstrated scientifically, it is evident that then the problem of the relations between the physical and the moral would come before us in a new aspect: it would be only a particular case of the law of the correlation of forces. We need not say that such a solution, restricted to experience, would

be neither spiritualistic nor materialistic, for those at least who care for the preciseness of the terms they employ.1

But not to dwell upon a problem which cannot be incidentally discussed, we will endeavour to deduce a conclusion from all that has been said, which shall be based, so far as possible, on experience. It appears that all contemporary schools, when we eliminate that which appertains to the exclusive point of view of each, tend more and more to consider physical and moral phenomena as identical. This conclusion seems perfectly natural, especially to those who take the ground of experience; so that we may say-at least, so far as current language will enable us to express ideas which are opposed to current opinions-that the physical is the moral looked

1 We may cite, in confirmation of what we have said, some remarkable reflections of the great English physicist, Tyndall. 'Granted,' says he, 'that a definite thought and a 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 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, 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. Let the consciousness of love, for example, be associated with a right-handed spiral motion of the molecules of the brain, and the consciousness of hate with a left-handed spiral motion. We should then know when we love that the motion is in one direction, and when we hate that the motion is in the other; but the "why" would remain as unanswerable as before.

'In affirming that the growth of the body is mechanical, and that thought, as exercised by us, has its correlative in the physics of the brain, I think the position of the "materialist" is stated, as far as that position is a tenable one. I think the materialist will be able finally to maintain this position against all attacks; but I do not think, in the present condition of the human mind, that he can pass beyond this position. I do not think he is entitled to say that his molecular groupings, and his molecular motions, explain everything. In reality they explain nothing. The utmost he can affirm is the association of two classes of phenomena, of whose real bond of union he is in absolute ignorance. The problem of the connection of body and soul is as insoluble in its modern form as it was in the prescientific ages.' Fragments of Science, vi.

at from without, and that the moral is the physical looked at from within. The difference between physical and moral is subjective, not objective; it pertains not to their own nature, but to our way of viewing them. Physics has demonstrated that heat, light, and sound appear to us as different, only because each of them is addressed to a different sense, so that all the difference comes from ourselves. The psychologist ought to see that the physical and the moral appear different to us, only because the one is cognized by the external senses and under the condition of time and space, and the other by the inner sense, under the condition of time; so that all the difference comes from ourselves. Thus the absolute, under its unconditioned form, would be entirely beyond our reach, and the conditioned forms in which it is manifested to us in experience would be opposites only by an illusion of our thought.

Perhaps we might proceed further, and draw an important deduction. If we admit the identity of physical and moral phenomena; if we observe that all that is in the living being forms a continuous series from perfect unconsciousness, if there be such a thing, to perfect consciousness;-if, again, there be such a thing; if it be borne in mind that the unconscious is the abyss into which everything enters and from which everything proceeds, the very root of all our mental life, and that our personality is like a wandering light on a vast and sombre lake, where it appears as though swallowed up each moment, then, perhaps, we shall be inclined to admit that the physical order and the moral order, which in our consciousness appear to be different things, are identical in the unconscious; that conscious duality is derived from an unconscious unity, so that in the unconscious, matter and thought, object and subject, external and internal, are one. This special reconciliation of the physical and moral in man would thus lead to the reconciliation of the object in general with the subject in general, of the universe with thought.

This, it is true, is a metaphysical hypothesis, but then it is neither possible nor desirable to give up metaphysics and hypothesis. This hypothesis has been put forward by men who are as sturdy upholders of experience as are to be found, and who have treated psychology as a natural science. If we admit,' says Wundt, 'the identity of physical and psychical facts, then the former will

come under the laws of mechanics, and the latter to those of logic, and it can be shown that these two kinds of laws are identical, and that the inner experience apprehends as a logical necessity what the outer experience perceives as a mechanical necessity.' 'This,' says he, in another place, 'is what the analysis of the process of sensation comes to, viz. that logical necessity and mechanical necessity differ not in their essence, but simply according to our way of regarding them. That which is given to us by psychological analysis as a continuity of logical operations (Schlüsse), is given us also by physiological analysis as a continuity of mechanical effects (Kraftwirkungen). . . . Logic and mechanism are identical; they are both only the form of essentially the same contents (gleichartigen Inhalt).1

CHAPTER II.

THE RELATIONS BETWEEN THE PHYSICAL AND THE MORAL. A PARTICULAR CASE.

We have just seen how the question of the general relations of the physical and the moral presents itself in our day. We would now pass from the theory to the facts, to consider a particular case, to resolve a single question, one, however, of capital importance for the matter in hand. The question is this :—

Must it be admitted that every psychological state, of whatever kind, has always a physiological state for its antecedent?

The correlation of the physical and the moral is universally admitted, but this belief, when examined, is very vague and very inexact. The general view, and, what is more serious still, many philosophical treatises, seem to admit that this correlation holds. good only in the gross, so to speak, and that frequently the body and the soul live each for itself. A few striking cases on either side are considered, all the rest being cast in the shade and forgotten. But, in fact, the thing is quite otherwise. Facts tend to

1 Menschen und Thierseele, 12th Lecture, p. 200, and 57th Lecture, p. 437.

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