[416] "We often begin to be dimly aware of a difference in a sensation or group of sensations, before we can assign any definite character to that which differs. Thus we detect a strange or foreign ingredient or flavor in a familiar dish, or of tone in a familiar tune, and yet are wholly unable for a while to say what the intruder is like. Hence perhaps discrimination may be regarded as the earliest and most primordial mode of intellectual activity." (Sully: Outlines of Psychology, p. 142. Cf. also G. H. Schneider: Die Unterscheidung, pp. 9-10.)
[417] In cases where the difference is slight, we may need, as previously remarked, to get the dying phase of n as well as of m before n-different-from-m is distinctly felt. In that case the inevitably successive feelings (as far as we can sever what is so continuous) would be four, m, difference, n, n-different-from-m. This slight additional complication alters not a whit the essential features of the case.
[418] Analysis. J. S. Mill's ed., ii, 17. Cf. also pp. 12, 14.
[419] There is only one obstacle, and that is our inveterate tendency to believe that where two things or qualities are compared, it must be that exact duplicates of both have got into the mind and have matched themselves against each other there. To which the first reply is the empirical one of "Look into the mind and see." When I recognize a weight which I now lift as inferior to the one I just lifted; when, with my tooth now aching, I perceive the pain to be less intense than it was a minute ago; the two things in the mind which are compared would, by the authors I criticise, be admitted to be an actual sensation and an image in the memory. An image in the memory, by general consent of these same authors, is admitted to be a weaker thing than a sensation. Nevertheless it is in these instances judged stronger; that is, an object supposed to be known only in so far forth as this image represents it, is judged stronger. Ought not this to shake one's belief in the notion of separate representative 'ideas' weighing themselves, or being weighed by the Ego, against each other in the mind? And let it not be said that what makes us judge the felt pain to be weaker than the imagined one of a moment since is our recollection of the downward nature of the shock of difference which we felt as we passed to the present moment from the one before it. That shock does undoubtedly have a different character according as it comes between terms of which the second diminishes or increases; and it may be admitted that in cases Where the past term is doubtfully remembered, the memory of the shock as plus or minus, might sometimes enable us to establish a relation which otherwise we should not perceive. But one could hardly expect the memory of this shock to overpower our actual comparison of terms, both of which are present (as are the image and the sensation in the case supposed), and make us judge the weaker one to be the stronger.—And hereupon comes the second reply: Suppose the mind does compare two realities by comparing two ideas of its own which represent them—what is gained? The same mystery is still there. The ideas must still be known; and, as the attention in comparing oscillates from one to the other, past must be known with present just as before. If you must end by simply saying that your 'Ego,' whilst being neither the idea of m nor the idea of n, yet knows and compares both, why not allow your pulse of thought, which is neither the thing m nor the thing n, to know and compare both directly? 'Tis but a question of how to name the facts least artificially. The egoist explains them, by naming them as an Ego 'combining' or 'synthetizing' two ideas, no more than we do by naming them a pulse of thought knowing two facts.
[420] I fear that few will be converted by my words, so obstinately do thinkers of all schools refuse to admit the unmediated function of knowing a thing, and so incorrigibly do they substitute being the thing for it. E.g., in the latest utterance of the spiritualistic philosophy (Bowne's Introduction to Psychological Theory, 1887, published only three days before this writing) one of the first sentences which catch my eye is this: "What remembers? The spiritualist says, the soul remembers; it abides across the years and the flow of the body, and gathering up its past, carries it with it" (p. 28). Why, for heaven's sake, O Bowne, cannot you say 'knows it'? If there is anything our soul does not do to its past, it is to carry it with it.
[421] Sensations of Tone, 2d English Ed., p. 65.
[422] Psychology, i, 345.
[423] A Budget of Paradoxes, p. 380.
[424] The explanation I offer presupposes that a difference too faint to have any direct effect in the way of making the mind notice it per se will nevertheless be strong enough to keep its 'terms' from calling up identical associates. It seems probable from many observations that this is the case. All the facts of 'unconscious' inference are proofs of it. We say a painting 'looks' like the work of a certain artist, though we cannot name the characteristic differentiæ. We see by a man's face that he is sincere, though we can give no definite reason for our faith. The facts of sense-perception quoted from Helmholtz a few pages below will be additional examples. Here is another good one, though it will perhaps be easier understood after reading the chapter on Space-perception than now. Take two stereoscopic slides and represent on each half-slide a pair of spots, a and b, but make their distances such that the a's are equidistant on both slides, whilst the b's are nearer together on slide 1 than on slide 2. Make moreover the distance ab = ab''' and the distance ab' = ab''. Then look successively at the two slides stereoscopically, so that the a's in both are directly fixated (that is fall on the two foveæ, or centres of distinctest vision). The a's will then appear single, and so probably will the b's. But the now single-seeming b on slide 1 will look nearer, whilst that on slide 2 will look farther than the a. But, if the diagrams are rightly drawn, b and b''' must affect 'identical' spots, spots equally far to the right of the fovea, b in the left eye and b''' in the right eye. The same is true of b' and b''. Identical spots are spots whose sensations cannot possibly be discriminated as such. Since in these two observations, however, they give rise to such opposite perceptions of distance, and prompt such opposite tendencies to movement (since in slide 1 we converge in looking from a to b, whilst in slide 2 we diverge), it follows that two processes which occasion feelings quite indistinguishable to direct consciousness may nevertheless be each allied with disparate associates both of a sensorial and of a motor kind. Cf. Donders, Archiv f. Ophthalmologie, Bd. 13 (1867). The basis of his essay is that we cannot feel on which eye any particular element of a compound picture falls, but its effects on our total perception differ in the two eyes.
