to its own distinctness when it entered into union with y. The same holds good for all other members of series which were presented before a disappeared from consciousness. Now a was most distinct when it fused with B, less so when it fused with y, and it became continually more obscured as it combined with one after another of the remaining members of the series. Hence it recalls ẞ more rapidly than y, and so on. The reproductive action of B, y, d, &c., is similar with respect to the parts of the series posterior to them. The result is that the whole train of presentations is successively revived in the same time-order in which it was originally given in sense-perception. This successive reproduction is called evolution of series.

If, instead of a, some posterior member of the original sense-series be immediately reproduced, it will recall not only the following, but also the anterior members. Thus, y will reproduce a, ẞ, as well as 8, e, . But there will be a fundamental difference in the way in which this takes place. y recalls 8, e,, successively, because it was itself in varying phases of intensity when it was co-presented with them, and it tends to raise them to full sensuous distinctness, because all possessed such distinctness when they were co-presented with it. On the other hand, it recalls a, ẞ not successively but simultaneously, because it entered simultaneously into combination with them, and it tends to raise them not to full sensuous distinctness, but only to that measure of distinctness which they possessed at the time when their union with it took place. Hence there is no evolution of series backwards, but only a simultaneous revival of anterior members in graduated phases of obscurity. This form of reproduction is called involution of series.

To complete the above statement it is necessary to note that in the evolution of a series the emergence of each successive member of it is accompanied by the subsidence of those which precede, just as in the original sense-given sequence. This is due partly to arrest from extraneous presentations and partly to the nature of the series itself. 7, in reproducing d, e, , occasions conflicts between d, e, Y, and a, B. Moreover, the arrest of a and ẞ must extend also to y, because it involves diminution of the residua of a and 8 beneath the measure of distinctness possessed by them, when they combined with y. Of course its reproductive energy will not be diminished by this increasing obscuration, except in so far as it sinks beneath the residual intensities which it possessed at the time of its fusion with other parts of the series.

Series similar to the above may be formed under other conditions. The presentations a, B, y, need not be originally given in a definite time-sequence in order that they may be reproduced in such a sequence. The same result may be due to their forming parts of a qualitative continuum, so that they can be arranged in an order of graduated contrast. If y be more contrary to a than it is to B, and if & be more contrary to a than to B, and more contrary to ẞ than to y, then, since intimacy of fusion is, ceteris paribus, inversely proportional to degree of contrariety, there will come into being, under favourable conditions, a series which evolves itself in an order corresponding to the qualitative affinity of its components. Series of this kind are of the greatest importance in the processes of classification and definite comparison.

$15. Correspondence of Mechanical Relations with Presented Relations. I have spoken hitherto only of the order in which presentations reinstate one another in consciousness; but the real import of the foregoing results, and, indeed, of the whole doctrine of psychological mechanism, can only be understood when regard is had to the way in which relations of the presentative activity are connected with relations constitutive of the presented content. The most important principle of correspondence may be stated thus:—În presented series quâ presented, the comparative nearness or remoteness of any two terms to a third depends, ceteris paribus, on the comparative intimacy their mechanical union has with it. For instance, if P is connected by a remnant r with II, and by a smaller remnant with II', then, ceteris paribus, the presented contents of II and II' will appear in consciousness as parts of a series in which II' is more remote from P than II is, and in which, therefore, II is intermediate between P and II'.

The parallelism of mechanical interaction and presented connexion could not have been treated with advantage before discussing the elementary modes of reproduction. It is necessary to draw attention to it here, both as a supplement to the preceding exposition and as a prelude to what follows. Up to this point I have spoken only of the way in which presentations become connected so as to form simple series. In order to complete the present instalment of my undertaking, and to lead up to the analytic portion of Herbart's work, I must say something about the way in which series, such as those above described, are connected with each other. This topic may conveniently be divided under three heads

(1) The mutual arrest and support of different series so far as this depends purely on the form of serial reproduction ; (2) The mutual curtailment of series;

(3) The manifold interweaving of series.

$16. Mutual Arrest and Support due to Serial Form. Series may arrest or support each other because of their contrariety or likeness, quá series, as distinguished from the likeness or contrariety of the presentations composing them. If, for instance, a sense-perception tends to reproduce simultaneously two pre-formed series in which the same presentations are differently arranged, the two orders of reproduction will be in conflict and will arrest each other. On the other hand. series which are similar in form support one another, and even revive each other by immediate reproduction. We are thus enabled to recognise a letter of the alphabet whether it be written in red ink or in black ink or in golden letters. The comparative ease with which we apprehend symmetrical figures is also to be referred to this head.1

§ 17. Mutual Curtailment of Series. Series shorten each other when they have the same beginnings and contrary continuations. Every presentation owing to the conditions of its genesis has a place in more than one series. When it first arises in sense-perception, it combines partly with other sense-given elements, partly with presentations which already pre-exist in consciousness, and partly with others which it reproduces immediately or causes to be reproduced immediately. Now, if we suppose one kind of presentation to be often repeated in sense-experience, it will have entered into a multitude of combinations. Hence, whenever it is reinstated in consciousness, it will tend to cause the evolution of a plurality of series discrepant partly in form and partly in the quality of their components. These series will conflict and mutually hinder each other from evolving, and, the longer the reproductive tendencies work, the greater will the conflict and reciprocal obscuration become. If we add to this that the obscuration of anterior members of an evolving series, when it goes beyond a certain point, impairs their efficiency in reproducing posterior members, it becomes obvious that curtailment of the antagonistic trains of ideas is bound to ensue. The central presentation in which they have their origin must, to a large extent, share the arrest of the series.

1 Psych., §§ 100, 114. Herbart's statements on this subject are somewhat meagre and vague.

338 G. F. STOUT: THE HERBARTIAN PSYCHOLOGY. (I.)

connected with it. But, if it has been sufficiently often repeated in sense-perception after renewal of susceptibility, it will be strong enough to maintain a comparatively high degree of conscious intensity. At the same time, the content of the central presentation will be in a manner isolated, because there will be no appreciable evolution of the diverging trains of presentations which meet in it as in a point of intersection. It can, therefore, to a certain extent, be considered apart from the special contexts in which it was presented to sense-perception at particular times and places. In this kind of mental formation lies the germ of the general concept.

§ 18. Interweaving of Series. Interweaving means that from each term of a given series trains of reproduction start, which are in their turn at once separated and interconnected by cross-series. On the side of the presented content regular mechanical interweaving is correlated with the consciousness of a spatial order, or of some order more or less analogous to the spatial; for example, the colourtriangle.

Besides this regular interweaving by which a perfect network is formed, there arise in the course of a varied experience all kinds and degrees of ramifying and re-entrant interconnexion. Where the components of a large group of presentations are connected in a more manifold and intimate manner with each other than they are with other parts of the total mental system, they form a relatively independent and separate mass. Varying environments and occupations give rise to the formation of many such masses in the developed human mind. At this point we are fairly on the threshold of Herbart's Analytic Psychology, the most important part of which is occupied in examining the interaction of the highly complex groups with each other and with sense-perception. The treatment of this part of the subject must be reserved for a second article.

II. SPACE AND TIME.

By ALEXANDER F. SHAND.

IN an article in the last No. of MIND (pp. 231-43) I argued that the objects of many fundamental kinds of knowledge transcend the Unity of Consciousness. I shall now consider, what I then excepted for independent treatment (p. 234), the reality which, in our knowledge of them, belongs to Space and Time. As the problem concerns the nature of this reality, it is not psychological but metaphysical. Of both I shall first assume, and endeavour to follow out to its consequences, the subjective doctrine, that they are images or forms constituted by the individual subject, and real only for it. First as regards Space.

From our representation of Space it seems, as Kant says, that we can think away all objects-all actual motion, solids, figures, lines and points. We appear to reach a homogenous unity, inseparable, indestructible. But this pure form of Space can have no parts; for I can only represent a part, and distinguish it from surrounding space, by drawing a figure, or suggesting it by a series of muscular sensations, or most vaguely of all by a concentration of attention. Nor has the pure form of Space any dimensions. We cannot realise the depth of Space without line. We plunge into it mentally; but this movement becomes a line, as we combine its points in unity. The breadth and height of it seem to stand facing us without requiring any linear construction. But the yaguest distinction of breadth from height requires two lines to be suggested in some way which intersect. We must then conclude that, if we succeed in banishing all line and figure from Space, we produce an image which has neither parts nor extension. Whether this is what the perception of Space once was, and its differentiation into a sum of extended parts an aftergrowth, or whether there was a vague extensiveness present to it in the beginning; whether again we can succeed in reaching this pure form of Space, or whether there is not some subtle movement of attention, or difference of form, ever playing upon its surface,-are psychological questions, which we are not here concerned about. My present contention is, that the possibility of Space possessing parts and dimensions