explained by symbols. Suppose that A and B are two related manifestations in the environment-say, the colour and taste of a fruit; then, so long as we contemplate their relation by itself, or as associated with other external phenomena, we are occupied with a portion of physical science. Now suppose that X and Y are the sensations produced in the organism by this peculiar light which the fruit reflects, and by the chemical action of its juice on the palate; then, so long as we study the action of the light on the retina and optic centres, and consider how the juice sets up in other centres a nervous change known as sweetness, we are occupied with facts belonging to the science of physiology. But we pass into the domain of psychology the moment we inquire how there comes to exist within the organism a relation between X and Y that in some way or other corresponds to the relation between A and B. Psychology is exclusively concerned with this connection between A B and XY: it has to investigate its nature, its origin, and its meaning."1 It is true, as the last chapter showed us, that biology also presupposes a reference to phenomena outside the organism, the very definition of Life being "the continuous adjustment of internal relations to external relations"; so that Mind here appears to be but the highest form of Life. We see here the difficulty of sharply demarcating adjacent provinces of na Nevertheless there is a broad distinction, though not a sharp one. Exclude from biological problems all those adjustments which constitute mental reaction upon the environment, and the only external factors remaining are those general conditions of temperature, moisture, food and the like, which are taken for granted once for all. While in each special problem of psychology, the relation between internal and external relations is the main subject of inquiry; on the other hand in special problems of biology, the relation between the internal processes and these general external 1 1 Spencer, Principles of Psychology, vol. i. p. 132. factors is not the chief, but a subordinate, subject of inquiry. Digestion, for instance, implies food; and "food implies neighbouring plants or animals; but this implication scarcely enters into our study of digestion, unless we ask the quite special question-how the digestive organs become fitted to the materials they have to act upon." But a moment's introspection will make it clear to everyone, "that he cannot frame any psychological conception without looking at internal coexistences and sequences in their adjustments to external coexistences and sequences. If he studies the simplest act of perception, as that of localizing a touch in some part of his skin, the indispensable terms of his inquiry are:--on the one hand a thing (1) and a position (2), both of which he regards as objective; and on the other hand a sensation (3), and a state of consciousness constituting his apprehension of position (4), both of which he regards as subjective. Or, if he takes for his problem one of his complex sentiments, as that of justice, he cannot represent to himself this sentiment, or give any meaning to its name, without calling to mind actions and relations supposed to exist in the environment: neither this nor any other emotion can be aroused in consciousness even vaguely, without positing something beyond consciousness to which it refers."1 Let us observe, in passing, that these considerations are quite incompatible with Materialism. The doctrine of the materialists rests partly on the assumption that the study of the laws of nervous action can give us a complete account of mental phenomena. But we have seen that to understand the simplest act of perception, we must take into the account not only the subjective and the objective factors, but the relation between the two. It is this relation which constitutes the perception. But this relation exists only in consciousness, and we cannot explain it save by direct observation of consciousness. Push our researches in biology as far as 1 Spencer, Principles of Psychology, vol. i. p. 133. we may, the most we can ever ascertain is that certain nervechanges succeed certain other nerve-changes or certain ex-ternal stimuli in a certain definite order. But all this of itself can render no account of the simplest phenomenon of consciousness. As Mr. Spencer well says, "such words as ideas, feelings, memories, volitions, have acquired their several meanings through self-analysis, and the distinctions we make between sensations and emotions, or between automatic acts and voluntary acts, can be established only by comparisons among, and classifications of, our mental states. The thoughts and feelings which constitute a consciousness, and are absolutely inaccessible to any but the possessor of that consciousness, form an existence that has no place among the existences with which the rest of the sciences deal. Though accumulated observations and experiments have led us by a very indirect series of inferences to the belief that mind and nervous action are the subjective and objective faces of the same thing, we remain utterly incapable of seeing, and even of imagining, how the two are related. Mind still continues to us a something without any kinship to other things." Thus we conclude that psychology-though, from the objective point of view, it may be regarded as a branch of biology in the same abstract sense in which biology may be regarded as a branch of geology, and geology as a branch of astronomy-has nevertheless an equal claim with any of these to be ranked as a distinct science. From the subjective point of view it has a superior claim to any of the others. Since here the phenomena studied are directly given in the consciousness of the investigator, there arises a distinction more fundamental than those by which the various departments of objective science are marked off from each other. And, indeed, without some of the data furnished by this unique subjective science, it is impossible to obtain the premises of philosophy; as will at once be admitted, on recollecting the topus which occupied us in the first part of this work. Psych.'ny is therefore distinct slike from biology an i from other sciences in its problems and in its theorems The problem of biology is to formulate the laws of nutrition and reproduction, muscular contraction and nervous irritation, Leredity and alaptation. The problem of psychology is to formulate the laws of Association,—the order in which certain relations among environing phenomena give rise to certain corresponding relations among our states of consciousness. And while the theorems of objective science in general are based upon the observation of objective phe nomena, whether external or internal to the organism; the theorems of psychology are based not only upon the observation of objective phenomena, but also upon the observation of subjective states. In view of these results, we see how hopelessly Comte went astray. Rejecting all introspection as metaphysical and delusive, he would have had us confine our inquiries to the succession of those nervous phenomena which are the invariable concomitants of feelings, ignoring the fact that without introspective observation we can never even ascertain that there is any invariable concomitance between the feelings and the nervous phenomena. He would have us solve a problem in which two factors are concerned, by investigating only one factor. In giving his reasons for thus rejecting all observation of consciousness, Comte reveals his inability (upon which I have already frequently remarked) to distinguish between psychology and metaphysics. He insists that psychologic inquiry, as hitherto conducted, has not resulted in discovery. If this were true, it would not help his case. Metaphysical psychologists have failed in discovery, not because they have directly examined states of consciousness, but because they have constructed unverifiable hypotheses about the nature of Mind in itself. Where they have abstained from ontological VOL. II. G inquiries, and have contented themselves with scientific methods, psychologists have made discoveries. To say nothing of such recent inquirers as Bain, Wundt, Fechner, and Taine, it may be fairly claimed that, among older speculators, Hobbes, Locke, Leibnitz, Berkeley, Hume, Kant, and Hartley, have by psychologic analysis made real and permanent contributions to our knowledge of mental operations. And at the very date when Comte was preparing his great treatise for publication, there appeared a remarkable book which, by establishing some of the fundamental laws of Association, went far toward placing psychology upon a scientific basis. It is not to the crude and superficial Gall, as Comte would have us believe, that we must give the respect due to the founder of scientific psychology: that respect is due, in far greater degree, to James Mill, the illustrious author of the "Analysis of the Human Mind." Nevertheless, while psychology is a science clearly distinct from biology, dealing with phenomena which may be classed as super-organic, and using introspective observation as one of its main implements of inquiry, it is no more than any other an absolutely independent science. Since the phenomena of Mind are never manifested to us save in connection with the phenomena of Life, and since the same general formula expresses the fundamental characteristics of the two groups of phenomena, it follows that no complete science of psychology can be constituted without the aid of biology. The conclusions reached by the analysis of subjective states must be shown to be in harmony with the conclusions reached by the synthesis of objective phenomena, before the scientific interpretation of Mind can be regarded as entirely satisfactory. The force of this statement becomes at once apparent, when we recollect that introspective observation can inform us only concerning the mental processes which go on in adult civilized men. In order to understand the genesis of these mental processes, we need the assistance of |