66 PSYCHOLOGY ultimately upon quasi-motor objects of varying intensity, the duration of which we do not directly experience as duration at all. They do endure and their intensity is a function of their duration ; but the intensity is all that we directly perceive. In other words, it is here contended that what Locke called an instant or moment "the time of one idea in our minds without the succession of another, wherein therefore we perceive no succession at all" is psychologically not "a part in duration" in that sense in which, as he says, "we cannot conceive any duration with- out succession" (Essay, ii. 16, 12). How do we know that the distance between our ideas cannot vary beyond certain bounds 1 This is not altogether a psychological question ; but we are perhaps entitled to note some interesting facts bearing upon it which may also serve to connect the perceptions of duration and suc- cession. If we make a Savart's wheel with a single tooth revolve slowly, say in three-quarters of a second, it will be found that in the long-run we estimate this interval correctly, slight overestimates and slight underestimates occurring indifferently. If we next place a second tooth opposite the first, letting the wheel revolve as before, so as to divide the three-quarters of a second into two inter- vals, we shall on the average overestimate it, and must increase the whole period to reach a new point of indiffer- ence. With two other teeth at right angles to the first two, the three-quarters of a second will appear longer still, and the time of a revolution must be still more increased before we shall cease to overestimate it. If we next employ, say, six teeth, 60 apart, the wheel revolving as at first, we shall detect ourselves attending to the alternate strokes, say to the first, third, and fifth, or perhaps to the third and the sixth ; in this way, though we continue to over- estimate the total period, we can note the number and regularity of the subdivisions. If these, however, be yet further increased, we can no longer reproduce them, though still aware that the whole period is divided into parts. But by the time we have introduced about fifteen equi- distant teeth, although there is physically an alternation of noise and silence as before, we perceive only a continu- ous hum, which steadily changes in quality as the number of teeth is further increased. Facts like these not only show that we estimate duration primarily by the effects of attention, but also make it probable that such estimate is fairly constant, since it is always approximately the same physical interval that becomes blurred. Further, we see that, where the distance between successive presentations is too short for a separate fixation of attention upon each, we proceed to take them in groups. This procedure is facilitated by differences in the quality and intensity of the objects as well as by differences in the intervals be- tween them ; hence among other things the aesthetic pro- perties of modulation and rhythm. Is time But, if our experience of time depends primarily upon acts of discrete attention to a succession of distinct objects, it would seem that or con- time, subjectively regarded, must be discrete and not continuous. tinuus? This, which is the view steadily maintained by the psychologists of Herbart's school, was implied if not stated by Locke, Berkeley, and Hume. Locke hopelessly confuses time as perceived and time as conceived, and can only save himself from pressing objections by the retort, "It is very common to observe intelligible dis- courses spoiled by too much subtlety in nice divisions." But Ber- keley and Hume with the mathematical discoveries of Newton and Leibnitz before them could only protest that there was nothing answering to mathematical continuity in our experience. And, whereas Locke had tried to combine with his general psychological account the inconsistent position that ' ' none of the distinct ideas we have of either [space or time] is without all manner of com- position," Berkeley declares, "For my own part, whenever I attempt to frame a simple idea of time, abstracted from the succession of ideas in my mind, which flows uniformly and is participated by all beings, I am lost and embrangled in inextricable difficulties. I have no notion of it at all, only I hear others say it is infinitely divisible, and speak of it in such a manner as leads me to harbour odd thoughts of my existence. . . . Time therefore being nothing, abstracted from the succession of ideas in our minds, it follows that the duration of any finite spirit must be estimated by the number of ideas or actions succeeding each other in that same spirit or mind " (Principles of Knowledge, i. 98). Hume, again, is at still greater pains to show that "the idea which we form of any finite quality is not infinitely divisible, but that by proper distinctions and separa- tions we may run this idea up to inferior ones, which will be perfectly simple and indivisible . . . that the imagination reaches a mini- mum, and may raise up to itself an idea of which it cannot conceive any subdivision, and which cannot be diminished without a total annihilation" (Human Nature, pt. ii. 1, Green's ed., p. 335). At the first blush we are perhaps disposed to accept this account of our time-perception, as Wundt, e.g., does, and to regard the attri- bution of continuity as wholly the result of after-reflexion. 1 But it may be doubted if this is really an exact analysis of the case. Granted that the impressions to which we chiefly attend are dis- tinct and discontinuous in their occupation of the focus of con- sciousness, and that, so far, the most vivid element in our time- experience is discrete ; granted further that in recollection and expectation such objects are still distinct all which seems to imply that time is a mere plurality yet there is more behind. The whole field of consciousness is not occupied by distinct objects, neither are the changes in this field discontinuous. The experi- mental facts above-mentioned illustrate the transition from a succession the members of which are distinctly attended to to one in which they are indistinctly attended to, i.e., are not dis- continuous enough to be separately distinguished. Attention does not move by hops from one definite spot to another, but, as Wundt himself allows, by alternate diffusion and concentration, like the foot of a snail, which never leaves the surface it is traversing. We have a clear presentation discerned as A or B when attention is gathered up ; and, when attention spreads out, we have confused presentations not admitting of recognition. But, though not recognizable, such confused presentations are represented, and so serve to bridge over the comparatively empty interval during which attention is unfocused. Thus our perception of a period of time is not comparable to so many terms in a series of finite units any more than it is to a series of infinitesimals. When attention is concentrated in expectation of some single impression, then, no doubt, it is brought to a very fine point ( " zugespitzt, " as Herbart would say) ; and a succession of such impressions would be repre- sented as relatively discrete compared with the representation of the scenery of a day-dream. But absolutely discrete it is not and cannot be. In this respect the truth is rather with Herbert Spencer, who, treating of this subject from another point of view, remarks, "When the facts are contemplated objectively, it becomes manifest that, though the changes constituting intelligence ap- proach to a single succession, they do not absolutely form one " (Psychology, i. 180, p. 403). On the whole, then, we may conclude that our concrete time-experiences are due to the simultaneous representa- tion of a series of definite presentations both accompanied and separated by more or fewer indefinite presentations more or less confused ; that, further, the definite presenta- tions have certain marks or temporal signs due to the movements of attention; that the rate of these movements or accommodations is approximately constant ; and that each movement itself is primarily experienced as an intensity. Feeling. Such summary survey as these limits allow of the more elementary facts of cognition is here at an end ; so far the most conspicuous factors at work have been those of what might be termed our ideational mechanism. In the higher processes of thought we have to take more account of mental activity and of the part played by language. But it seems preferable, before entering upon this, to explore also the emotional and active constituents of mind in their more elementary phases. In our preliminary survey we have seen that psychical life consists in the main of a continuous alternation of receptive and reactive consciousness, i.e., in its earliest form, of alternations of sensation and movement. At a later stage we find that in the receptive phase ideation is added to sensation, and that in the active phase thought and fancy, or the voluntary manipulation and control of the idea- tional trains, are added to the voluntary manipulation and control of the muscles. At this higher level also it is possible that either form of receptive consciousness may lead to either form of active : sensations may lead to thought rather than to action in the restricted 1 Comp. Wundt, Logik, vol. i. p. 432.
