is not necessary to suppose, as Freud seems to do, that every unconscious wish was once conscious, and was then, in his terminology, "repressed" because we disapproved of it. On the contrary, we shall suppose that, although Freudian "repression" undoubtedly occurs and is important, it is not the usual reason for unconsciousness of our wishes. The usual reason is merely that wishes are all, to begin with, unconscious, and only become known when they are actively noticed. Usually, from laziness, people do not notice, but accept the theory of human nature which they find current, and attribute to themselves whatever wishes this theory would lead them to expect. We used to be full of virtuous wishes, but since Freud our wishes have be-come, in the words of the Prophet Jeremiah, "deceitful above all things and desperately wicked." Both these views, in most of those who have held them, are the product of theory rather than observation, for observation requires effort, whereas repeating phrases does not. * Cf. Hart, "The Psychology of Insanity," p. 19. The interpretation of unconscious wishes which I have been advocating has been set forth briefly by Professor John B. Watson in an article called "The Psychology of Wish Fulfilment," which appeared in "The Scientific Monthly" in November, 1916. Two quotations will serve to show his point of view: "The Freudians (he says) have made more or less of a 'metaphysical entity' out of the censor. They suppose that when wishes are repressed they are repressed into the 'unconscious,' and that this mysterious censor stands at the trapdoor lying between the conscious and the unconscious. Many of us do not believe in a world of the unconscious (a few of us even have grave doubts about the useful-ness of the term consciousness), hence we try to explain censorship along ordinary biological lines. We believe that one group of habits can 'down' another group of habits--or instincts. In this case our ordinary system of habits--those which we call expressive of our 'real selves'--inhibit or quench (keep inactive or partially inactive) those habits and instinctive tendencies which belong largely 11 in the past"(p. 483). Again, after speaking of the frustration of some impulses which is involved in acquiring the habits of a civilized adult, he continues: "It is among these frustrated impulses that I would find the biological basis of the unfulfilled wish. Such 'wishes' need never have been 'conscious,' and NEED NEVER HAVE BEEN SUPPRESSED INTO FREUD'S REALM OF THE UNCONSCIOUS. It may be inferred from this that there is no particular reason for applying the term 'wish' to such tendencies"(p. 485). One of the merits of the general analysis of mind which we shall be concerned with in the following lectures is that it removes the atmosphere of mystery from the phenomena brought to light by the psycho-analysts. Mystery is delightful, but unscientific, since it depends upon ignorance. Man has developed out of the animals, and there is no serious gap between him and the amoeba. Something closely analogous to knowledge and desire, as regards its effects on behaviour, exists among animals, even where what we call "consciousness" is hard to believe in; something equally analogous exists in ourselves in cases where no trace of "consciousness" can be found. It is therefore natural to suppose that, what ever may be the correct definition of "consciousness," "consciousness" is not the essence of life or mind. In the following lectures, accordingly, this term will disappear until we have dealt with words, when it will re-emerge as mainly a trivial and unimportant outcome of linguistic habits. LECTURE II. INSTINCT AND HABIT In attempting to understand the elements out of which mental phenomena are compounded, it is of the greatest importance to remember that from the protozoa to man there is nowhere a very wide gap either in structure or in behaviour. From this fact it is a highly probable inference that there is also nowhere a very wide mental gap. It is, of course, POSSIBLE that there may be, at certain stages in evolution, elements which are entirely new from the standpoint of analysis, though in their nascent form they have little influence on behaviour and no very marked correlatives in structure. But the hypothesis of continuity in mental development is clearly preferable if no psychological facts make it impossible. We shall find, if I am not mistaken, that there are no facts which refute the hypothesis of mental continuity, and that, on the other hand, this hypothesis affords a useful test of suggested theories as to the nature of mind. The hypothesis of mental continuity throughout organic evolution may be used in two different ways. On the one hand, it may be held that we have more knowledge of our own minds than those of animals, and that we should use this knowledge to infer the existence of something similar to our own mental processes in animals and even in plants. On the other hand, it may be held that animals and plants present simpler phenomena, more easily analysed than those of human minds; on this ground it may be urged that explanations which are adequate in the case of animals ought not to be lightly rejected in the case of man. The practical effects of these two views are diametrically opposite: the first leads us to level up animal intelligence with what we believe ourselves to know about our own intelligence, while the second leads us to attempt a levelling down of our own intelligence to something not too re-mote from what we can observe in animals. It is therefore important to consider the relative justification of the two ways of applying the principle of continuity. It is clear that the question turns upon another, namely, which can we know best, the psychology of animals or that of human be-ings? If we can know most about animals, we shall use this knowledge as a basis for inference about human beings; if we can know most about human beings, we shall adopt the opposite procedure. And the question whether we can know most about the psychology of human beings or about that of animals turns upon yet another, namely: Is introspection or external observation the surer method in psychology? This is a question which I propose to discuss at length in Lecture VI; I shall therefore content myself now with a statement of the conclusions to be arrived at. We know a great many things concerning ourselves which we cannot know nearly so directly concerning animals or even other peo-ple. We know when we have a toothache, what we are thinking of, what dreams we have when we are asleep, and a host of other occurrences which we only know about others when they tell us of them, or otherwise make them inferable by their behaviour. Thus, so far as knowledge of detached facts is concerned, the advantage is on the side of self-knowledge as against external observation. But when we come to the analysis and scientific understanding of the facts, the advantages on the side of self-knowledge become far less clear. We know, for example, that we have desires and beliefs, but we do not know what constitutes a desire or a belief. The phenomena are so familiar that it is difficult to realize how little we really know about them. We see in animals, and to a lesser extent in plants, behaviour more or less similar to that which, in us, is prompted by desires and beliefs, and we find that, as we descend 12 in the scale of evolution, behaviour becomes simpler, more easily reducible to rule, more scientifically analysable and predictable. And just because we are not misled by familiarity we find it easier to be cautious in interpreting behaviour when we are dealing with phenomena remote from those of our own minds: Moreover, introspection, as psychoanalysis has demonstrated, is extraordinarily fallible even in cases where we feel a high degree of certainty. The net result seems to be that, though self-knowledge has a definite and important contribution to make to psychology, it is exceedingly misleading unless it is constantly checked and controlled by the test of external observation, and by the theories which such observation suggests when applied to animal behaviour. On the whole, therefore, there is probably more to be learnt about human psychology from animals than about animal psychology from human beings; but this conclusion is one of degree, and must not be pressed beyond a point. It is only bodily phenomena that can be directly observed in animals, or even, strictly speaking, in other human beings. We can observe such things as their movements, their physiological processes, and the sounds they emit. Such things as desires and beliefs, which seem obvious to introspection, are not visible directly to external observation. Accordingly, if we begin our study of psychology by external observation, we must not begin by assuming such things as desires and beliefs, but only such things as external observation can reveal, which will be characteristics of the movements and physiological processes of animals. Some animals, for example, always run away from light and hide themselves in dark places. If you pick up a mossy stone which is lightly embedded in the earth, you will see a number of small animals scuttling away from the unwonted daylight and seeking again the darkness of which you have deprived them. Such animals are sensitive to light, in the sense that their movements are affected by it; but it would be rash to infer that they have sensations in any way analogous to our sensations of sight. Such inferences, which go beyond the observable facts, are to be avoided with the utmost care. It is customary to divide human movements into three classes, voluntary, reflex and mechanical. We may illustrate the distinction by a quotation from William James ("Psychology," i, 12): "If I hear the conductor calling 'all aboard' as I enter the depot, my heart first stops, then palpitates, and my legs
