46 PSYCHOLOGY urge such objections is to miss the drift of our discussion, and to answer them may serve to make it clearer. Where silence can be broken there are representations of preced- ing .sounds and in all probability even subjective pre- sentations of sound as well ; silence as experienced by one who has heard is very different from the silence of Con- dillac's statue before it had ever heard. The question is rather whether such a conception as that of Condillac's is possible ; supposing a sound to be, qualitatively, entirely distinct from a smell, could a field of consciousness consist- ing of smells be followed at once by one in which sounds had part 1 And, as regards the blind coming to see, we must remember not only that the "blind have eyes but that they are descended from ancestors who could see. What nascent presentations of sight are thus involved it would be hard to say ; and the problem of heredity is one that we have for the present left aside. The view here taken is (1) that at its first appearance in psychical life a new sensation or so-called elementary presentation is really a partial modification of some pre- existing presentation, which thereby becomes as a whole more complex than it was before ; and (2) that this com- plexity and differentiation of parts never become a plural- ity of discontinuous presentations, having a distinctness and individuality such as the atoms or elementary particles of the physical world are supposed to have. Beginners in psychology, and some who are not beginners, are apt to be led astray by expositions which begin with the sensa- tions of the special senses, as if these furnished us with the type of an elementary presentation. The fact is we never experience a mere sensation of colour, sound, touch, and the like ; and what the young student mistakes for such is really a perception, a sensory presentation combined with various sensory and motor presentations and with representations and having thus a definiteness and com- pleteness only possible to complex presentations. More- over, if we could attend to a pure sensation of sound or colour by itself, there is much to justify the suspicion that even this is complex and not simple, and owes to such complexity its clearly marked specific quality. In certain of our vaguest and most diffused organic sensa- tions, in which we can distinguish little besides variations in intensity and massiveness, there is probably a much nearer approach to the character of the really primitive presentations. Diffusion The importance of getting a firm grasp of this concep- and re- tj on o f a presentation-continuum as fundamental to the lon * whole doctrine of presentations will justify us in ignoring a little longer the details of actual mental development and regarding it first from this more general point of view. In a given sensation, more particularly in our organic sensations, we can distinguish three variations, viz., variations of quality, of intensity, and of what Dr Bain has called massiveness, or, as we will say, extensity. This last characteristic, which everybody knows who knows the difference between the ache of a big bruise and the ache of a little one, between total and partial immersion in a bath, is, as we shall see later on, an essential element in our perception of space. But it is certainly not the whole of it, for in this experience of massive sensation alone it is impossible to find other elements which an analysis of spatial intuition unmistakably yields. Exten- sity and extension, then, are not to be confounded. Now we find, even at our level of mental evolution, that an increase in the intensity of a sensation is apt to entail an increase in its extensity too ; this is still more apparent in the case of movements, and especially in the movements of the young. In like manner we observe a greater extent of movement in emotional expression when the intensity of the emotion increases. Even the higher region of ima- gination is no exception, as is shown by the whirl and confusion of ideas incident to delirium, and, indeed, to all strong excitement. But this " diffusion " or " radiation," as it has been called, diminishes as we pass from the class of organic sensations to the sensations of the five senses, from movements expressive of feeling to movements de- finitely purposive, and from the tumult of ideas excited by passion to the steadier sequences determined by efforts to think. Increased differentiation seems, then, to be inti- mately connected with increased " restriction." The causal relations of the two must be largely matter of conjecture and cannot be fully discussed here. Probably there may be found certain initial differentiations which for psycho- logy are ultimate facts that it cannot explain. But, such differentiations being given, then it may be safely said that, in accordance with what we have called the principle of subjective selection (see p. 42), attention would be voluntarily concentrated upon some of them and voluntary movements specially connected with these. To such subjectively initiated modifications of the presentation- continuum, moreover, we may reasonably suppose " re- striction" to be in large measure due. But increased restriction would render further differentiation of the given presentation possible and so the two processes might supplement each other. But, be their interaction what it may, these processes have now proceeded so far that at the level of human consciousness we find it hard to form any tolerably clear conception of a field of con- sciousness in which an intense sensation, no matter what, might diffuse over the whole. Colours, e.g., are with us so distinct from sounds that except as regards the drain upon attention there is nothing in the intensest colour to affect the simultaneous presentation of a sound. But at the beginning whatever we regard as the earliest differ- entiation of sound might have been incopresentable with the earliest differentiation of colour, if sufficiently diffused, just as now a field of sight all blue is incopresentable with one all red. Or, if the stimuli appropriate to both were active together, the resulting sensation might have been what we should describe as a blending of the two, as purple is a blending of red and violet. Now, on the other hand, colours and sounds are necessarily so far localized that we are directly aware that the eye is concerned with the one and the ear with the other. This brings to our Inco- notice a fact so ridiculously obvious that it has never been P deemed worthy of mention, and yet it has undeniably im- portant bearings the fact, viz., that certain sensations or movements are an absolute bar to the simultaneous pre- sentation of other sensations or movements. We cannot see an orange as at once yellow and green, though we can feel it at once as both smooth and cold ; we cannot open and close the same hand at the same moment, but we can open one hand while closing the other. Such incopresent- ability or contrariety is thus more than mere difference, and occurs only between presentations belonging to the same sense or to the same group of movements. Strictly speaking, it does not always occur even then ; for red and yellow, hot and cold, are presentable together provided they have certain other differences which we shall meet again presently as differences of local sign. In the preceding paragraphs we have had occasion to Reten distinguish between the presentation-continuum or whole tiveM field of consciousness, as we may for the present call it, and those several modifications within this field which are ordinarily spoken of as presentations, and to which now that their true character as parts is clear we too may confine the term. But it will be well in the next place, before inquiring more closely into their characteristics, to consider for a moment that persistence of preceding modi- fications which the differentiation of the presentation-
