also similar to a foot-ball; but a gas-jet and a foot-ball are not similar to each other. When we affirm the similarity of two compound things, we should always say in what respect it obtains. Moon and gas-jet are similar in respect of luminosity, and nothing else; moon and foot-ball in respect of rotundity, and nothing else. Foot-ball and gas-jet are in no respect similar-that is, they possess no common point, no identical attribute. Similarity, in compounds, is partial identity. When the same attribute appears in two phenomena, though it be their only common property, the two phenomena are similar in so far forth. To return now to our associated representations. If the thought of the moon is succeeded by the thought of a foot-ball, and that by the thought of one of Mr. X's railroads, it is because the attribute rotundity in the moon broke away from all the rest and surrounded itself with an entirely new set of companions-elasticity, leathery integument, swift mobility in obedience to human caprice, etc.; and because the last-named attribute in the foot-ball in turn broke away from its companions, and, itself persisting, surrounded itself with such new attributes as make up the notions of a railroad king,' of a rising and falling stock-market, and the like.

The gradual passage from total to focalized, through what we have called ordinary partial, recall may be sym

B

FIG. 58.

bolized by diagrams. Fig. 58 is total, Fig. 59 is partial, and Fig. 60 focalized, recall. A in each is the passing,

B the coming, thought. In 'total recall,' all parts of A are equally operative in calling up B. In partial recall,' most parts of A are inert. The part M alone breaks out and awakens B. In similar association or focalized recall,' the part M is much smaller than in the previous case,

FIG 59.

and after awakening its new set of associates, instead of fading out itself, it continues persistently active along with them, forming an identical part in the two ideas, and making these, pro tanto, resemble each other.*

Why a single portion of the passing thought should break out from its concert with the rest and act, as we say, on its own hook, why the other parts should become inert. are mysteries which we can ascertain but not explain.

* Miss M. W. Calkins (Philosophical Review, I. 389, 1892) points out that the persistent feature of the going thought, on which the association in cases of similarity hinges, is by no means always so slight as to warrant the term 'focalized.' "If the sight of the whole breakfast-room be followed by the visual image of yesterday's

Possibly a minuter insight into the laws of neural action. will some day clear the matter up; possibly neural laws will not suffice, and we shall need to invoke a dynamic reaction of the consciousness itself. But into this we cannot enter now.

Voluntary Trains of Thought.-Hitherto w have assumed the process of suggestion of one object by another to be spontaneous. The train of imagery wanders at its own sweet will, now trudging in sober grooves of habit, now with a hop, skip, and jump, darting across the whole field of time and space. This is revery, or musing; but great segments of the flux of our ideas consist of something very different from this. They are guided by a distinct purpose or conscious interest; and the course of our deas is then called voluntary.

Physiologically considered, we must suppose that a purpose means the persistent activity of certain rather definite brain-processes throughout the whole course of thought. Our most usual cogitations are not pure reveries, absolute driftings, but revolve about some central interest or topic to which most of the images are relevant, and towards which we return promptly after occasional digressions.

breakfas“-table, with the same setting and in the same surroundings, the association is practically total," and yet the case is one of similarity. For Miss Calkins, accordingly, the more important distinction is that between what she calls desistent and persistent association. In 'desistent' association all parts of the going thought fade out and are replaced. In 'persistent' association some of them remain, and form a bond of similarity between the mind's successive objects; but only where this bond is extremely delicate (as in the case of an abstract relation or quality) is there need to call the persistent process 'focalized.' I must concede the justice of Miss Calkins's criticism, and think her new pair of terms a useful contribution. Wundt's division of associations into the two classes of external and internal is congruent with Miss Calkins's division. Things associated internally must have some element in common; and Miss Calkins's word 'persistent' suggests how this may cerebrally come to pass. 'Desistent,' on the other hand, suggests the process by which the successive ideas become external to each other or preserve no inner tie.

This interest is subserved by the persistently active braintracts we have supposed. In the mixed associations which we have hitherto studied, the parts of each object which form the pivots on which our thoughts successively turn have their interest largely determined by their connection with some general interest which for the time has seized upon the mind. If we call Z the brain-tract of general interest, then, if the object abc turns up, and b has more associations with Z than have either a or c, b will become the object's interesting, pivotal portion, and will call up its own associates exclusively. For the energy of b's braintract will be augmented by Z's activity,-an activity which, from lack of previous connection between Z and a and Z and c, does not influence a or c. If, for instance, I think of Paris whilst I am hungry, I shall not improbably find that its restaurants have become the pivot of my thought, etc., etc.

Problems. But in the theoretic as well as in the practical life there are interests of a more acute sort, taking the form of definite images of some achievement which we desire to effect. The train of ideas arising under the influence of such an interest constitutes usually the thought of the means by which the end shall be attained. If the end by its simple presence does not instantaneously suggest the means, the search for the latter becomes a problem; and the discovery of the means forms a new sort of end, of an entirely peculiar nature-an end, namely, which we intensely desire before we have attained it, but of the nature of which, even whilst most strongly craving it, we have no distinct imagination whatever (compare pp. 241–2). The same thing occurs whenever we seek to recall something forgotten, or to state the reason for a judgment which we have made intuitively. The desire strains and presses in a direction which it feels to be right, but towards a point which it is unable to see. In short, the absence of an item is a determinant of our representations quite as Positive as its presence can ever be. The gap becomes no

mere void, but what is called an aching void. If we try to explain in terms of brain-action how a thought which only potentially exists can yet be effective, we seem driven to believe that the brain-tract thereof must actually be excited, but only in a minimal and sub-conscious way. Try, for instance, to symbolize what goes on in a man who is rack ing his brains to remember a thought which occurred to him last week. The associates of the thought are there, many of them at least, but they refuse to awaken the thought itself. We cannot suppose that they do not irradiate at all into its brain-tract, because his mind quivers ou the very edge of its recovery. Its actual rhythm sounds in his ears; the words seem on the imminent point of fol lowing, but fail (see p. 165). Now the only difference between the effort to recall things forgotten and the search after the means to a given end is that the latter have not, whilst the former have, already formed a part of our experience. If we first study the mode of recalling a thing forgotten, we can take up with better understanding the voluntary quest of the unknown.

Their Solution.-The forgotten thing is felt by us as a gap in the midst of certain other things. We possess a dim idea of where we were and what we were about when it last occurred to us. We recollect the general subject to which it pertains. But all these details refuse to shoot together into a solid whole, for the lack of the missing thing, so we keep running over them in our mind, dissatisfied, craving something more. From each detail there radiate lines of association forming so many tentative guesses. Many of these are immediately seen to be irrelevant, are therefore void of interest, and lapse immediately from consciousness. Others are associated with the other details present, and with the missing thought as well. When these surge up, we have a peculiar feeling that we are warm,' as the children say when they play hide and seek; and such associates as these we clutch at and keep before the attention. Thus we recollect successively that when we last were considering the