to Clifford's view, which have had a common origin in the most characteristic tendencies of modern thought-but as isolated suggestions of more or less merit, though of no real importance. Yet in the essay itself the remark is made that the view set forth there is one to which speculation has been tending for some time. And it may be shown by considering the theory of mind-stuff from the historical point of view, that it is the final form of a metaphysical doctrine which has been developed under the influence of the methods and results of physical and psychological science, but which, unlike some speculations that are scientific in their origin,1 can be maintained against sceptical criticism; and, consequently, that it has strong claims on the attention of those who wish to arrive at a consistent view of things and who regard a metaphysical doctrine as the end of scientific research. In order to prove that all this is so, it will be necessary to describe briefly certain results of biological and psychological study which have rendered possible a metaphysical doctrine founded on science. When this has been done, it will be seen that Clifford's theory is a real attempt at a new construction in metaphysics. A historical account of the theory of mind-stuff may also serve to conciliate those who are suspicious of any theory that looks new and is ingenious and clearly expressed; for it will remove the paradoxical character by which clear and ingenious theories are generally affected. Afterwards, to make the doctrine of mind-stuff seem quite satisfactory, it must be defended as far as possible against the arguments of transcendentalists. It is therefore desirable, before tracing the historical development of Clifford's view, to consider the attitude of the transcendental and empirical schools towards one another. By this consideration of the position of the rival schools of

1 Prof. Royce, in his article on "Mind-stuff' and Reality," in MIND XXIII., seems to regard Clifford's theory as one of the forms of realism referred to here, and therefore as an attempt to revive a conception that has often been tried before in philosophy and has been found a failure. His first objection to it is that if it offers the current monistic' explanation of the connexion between physical and psychical facts," then it is "merely a sort of scholasticism revived"; it is the substitution of a "worn-out metaphor," of a "fiction of language," for a scientific statement of the fundamental opposition of mental and physical phenomena. But the theory of Mind-stuff is shown by the historical view of it to be something quite different from the attempts that have been made to restore the conception of Substance either in its monistic or in its dualistic sense; for it was put forth by philosophers who had accepted the negative conclusions of idealism, and idealism is an essential part of it. That is, this theory, considered in its relations to modern metaphysics, is in the direct line of development, while the ordinary monistic systems are provisional theories devised for the sake of giving verbal consistency to a purely scientific view of things, or, as Prof. Royce calls them, "a sort of scholasticism revived".

metaphysics, the kind of objections that Clifford's theory has to meet will be indicated in advance, and at the same time it will be made evident that there was need for some such theory.

I.

The disciples of Kant and Hegel are fond of remarking that since the time of Hume those who belong to the same school of thought as Hume and his predecessors have given up all attempt at pure philosophy, and have confined themselves to psychology and the classification of the sciences. But, they say, the result of Hume's philosophy was not a result that ought to have been taken as final. It was only by concessions to " common-sense that the philosophy of Hume could be made to seem as if it left room for science. Philosophers ought to have attempted a new construction which should be proof against scepticism, and not to have given up metaphysics as impossible; for a metaphysical doctrine is necessary as a basis even for physical science, and empirical psychology is not sufficient as a substitute for metaphysics. The reply that is usually made by the modern empirical school is, that the philosophy of those who declared experience to be the only source of knowledge was incomplete till the true way of meeting the difficulties pointed out by Kant had been suggested by the theory of Evolution. This answer is to a certain extent satisfactory, but that it is not entirely so is shown by the fact that those who have seen the importance of the theory of Evolution in psychology have not found idealism or scepticism sufficient as a metaphysical doctrine. The 'transformed realism" of Spencer and the "reasoned realism" of Lewes, for example, have been put forth in opposition to idealism and scepticism. But neither of these views has been generally accepted by those who are disposed to accept as a whole the system of philosophy founded on Evolution. "Transformed realism" and "reasoned realism are not able to maintain themselves against idealistic and sceptical criticism, and therefore many admirers of the philosophers who advocate these theories are content to go without a metaphysical doctrine altogether. On the other hand, the Hegelians say they have a system which contains in itself an answer to all scepticism as to the possibility of metaphysics. But their system has not had its form determined by scientific method, and consequently does not serve to explain the generalisations of science, but seems something quite apart from them. For this reason Hegelianism does not commend itself to those who wish to see unity introduced among the conceptions of modern science. Now if it can be shown that

the theory of "mind-stuff," while it is founded on a scientific view of things like the theories of "transformed realism" and "reasoned realism," at the same time does not make any attempt to escape from the necessity that is imposed on modern metaphysics of giving up all pretence of restoring the forms of ontology that were destroyed by Hume and Berkeley, then something will have been done towards proving that the system of Hegel was a premature attempt at reconstruction in metaphysics, and that the only way to arrive at a new point of view capable of superseding dualism was to study psychology and physical science for the sake of their suggestions, until a sufficient number of suggestions for a general theory of knowledge had been accumulated to make it possible to select from them those that are appropriate.

Up to the present time it has not been noticed that Clifford's theory reduced to its simplest form is identical with Schopenhauer's metaphysics of the Will. When the two theories are compared, it is obvious that Clifford's "elementary feeling" corresponds to Schopenhauer's "will as thing-in-itself". Schopenhauer explains that by "will" he does not mean anything like an actual volition, but a kind of fundamental feeling for which "will" is a better term than any other, since it suggests to the mind the element in actual consciousness that is most opposed to distinct cognition, and since this is the element that must be regarded as primitive. More recently the distinction here pointed out by Schopenhauer has been expressed in Mr. Spencer's classification of states of consciousness into "feelings" and "relations between feelings". Mr. Spencer himself has suggested the theory of mind-stuff as a possible view in the chapter in his Principles of Psychology on the "Substance of Mind," but has not developed it. Still it is clear that his classification of states of consciousness has led to an improved statement of the theory, for the term "feeling" is less open to objection than the term "will" as the name of that which is primitive in mind.

The importance of Schopenhauer's anticipation of the theory of mind-stuff will be seen when it is considered that Schopenhauer professed to found his metaphysics on science, and that at the same time he was, like Clifford, an idealist; his idealism having however been arrived at by the study of Kant rather than of Berkeley and Hume. As to his metaphysical theory of the Will, he asserted that it was a translation into philosophical terms of the physiological doctrines of Cabanis and Bichat. According to a French critic who wrote on the subject not very long since, all the characteristic doctrines of English and German physiological psychology are implicit in the works of

these physiologists. Even if we admit that some of the conclusions of modern schools may have been read into the statements of the earlier writers, yet in order that such a position as that of the critic referred to can be taken up, there must be many things in Cabanis and Bichat capable of having suggested to Schopenhauer the ideas possessed by the modern schools of psychology. Since Clifford undoubtedly found suggestions in these ideas, the historical parallelism between his theory and Schopenhauer's is very close. Not only have both theories their origin in science but also in the same group of scientific ideas.

The ideas that have done most to make contemporary psychology different from the psychology of the older empirical school are: (1) the distinction that has been drawn between consciousness, sub-consciousness, and unconsciousness as modes of sensibility differing only in degree, the older psychologists having taken into account only those elements of mind that emerge into full consciousness; (2) the application of the biological theory of Evolution to psychology; (3) the discovery by some German psychologists that the methods of experimental physiology may be applied to the psychology of the senses.

Schopenhauer's system was suggested by the first of these ideas. He set out with a theory of the external world held in common by himself and all idealists since Berkeley. In explaining this view he uses the terminology of Kant and distinguishes between the "representation" and the "thing-in-itself". The external world belongs to the representation and is often spoken of by Schopenhauer as "Maya" or illusion. Clifford makes use of the same term-representation-in setting forth the idealistic part of his theory. Sometimes the objection is made to this term that "it implies something representing and something represented". But the same answer may be given to this as to similar criticisms on Berkeley's "ideas" and Hume's "ideas and impressions". These philosophers had to explain that they used such terms merely as descriptive terms; they requested their readers to get rid as far as possible of all associations of the words "idea" and "impression" with the metaphors from which they are derived, and with physical hypotheses. The word "representation" has similar associations, and this must be borne in mind when it is employed as a philosophical term. After selecting from previous systems his metaphysics of the external world, the question occurred to Schopenhauer as to Clifford, What is the nature of the thing-in-itself? and he answered it in the same way. The criticism of Hume had made it impossible to accept Berkeley's view that "the substance of mind" is the thing-in-itself; and the empirical psycho

logy by which all consciousness is resolved into impressions and ideas derived from impressions, was not found adequate as an explanation of things, for the "impressions" of Hume are merely portions of the "representation". The problem that demanded solution was to find something having the nature of mind but deeper than definite consciousness. If this could be found, and could be shown to be capable of explaining actual consciousness so far as explanation is possible, then the problem might be considered as solved.

The facts of physiology have at length led psychologists to see that the series of states of consciousness which it is possible to observe and classify by means of the introspective method alone forms only a portion of the mental life, that definite consciousness has a background of sub-consciousness and unconsciousness. At first it seems like a contradiction to speak of facts of unconsciousness as belonging to psychology; but when it is considered that the same changes in the nervous system may be accompanied according to circumstances by vivid changes in consciousness or by some sub-conscious change or may have no mental concomitant that can be detected by introspection, then it becomes evident that mind must be regarded as consisting of other elements besides those that appear in distinct consciousness; for it is absurd to suppose that the same nervous change taken by itself has different mental concomitants at different times. This conception, suggested by physiology, that mind is made up of elements which may be combined into what is called consciousness, but which, taken alone, are unconscious," is really implied in the ordinary introspective psychology. The elements into which complex states of consciousness are resolved by analysis are not immediately perceptible in those states; the laws of association must be understood before the elements of actual consciousness can be detached; hence these elements may be called "unconscious". But the study of physiology was necessary to bring out clearly the conception of "unconscious feelings" as factors in mental phenomena. These elements of mind disclosed by physiology were regarded by Schopenhauer as the reality underlying all phenomenal existence, and the fundamental element in mind was called by him the Will. This term was selected because of the antithesis that there is between "will" and "intelligence"; intelligence-definite cognition-constitutes mind as we know it in its highest form; the term "will" is applied to what is regarded as the irrational element in mind-that which is irrational because it is more fundamental than reason. Now if the term "unconsciousness" as applied to mind is once admitted, it is impossible to stop short of admitting that every change in the