CHAPTER XXV.

THE RELATION OF SEQUENCE.

374 As was said in the last chapter, this remaining relation is but another side of the one there treated of. Sequence is change; and change, as known by us, is the unlikeness of a present state of consciousness to a past state. While on the one hand, the two terms of the relation of unlikeness cannot be known without a change in consciousness, on the other hand, there cannot be a change in consciousness without there being two states standing in a relation of unlikeness. The fundamental or undecomposable relation must have two terms-two juxtaposed states of consciousness. These must be unlike, otherwise they will constitute not two states but one. To be known as unlike they must be known in succession, since consciousness cannot be in two states at the same time. The ultimate relation, therefore, is nothing more than a change in the state of consciousness; and we call it either a relation of unlikeness or a relation of sequence, according as we think of the contrast between the antecedent and consequent states, or of their order.

Beyond thus describing each aspect of this relation in terms of the other aspect, no account can be given of it. Like every primordial experience-like the sensation of redness or that of warmth, it transcends analysis. All that is left to be done is to classify the relations of sequence, and

to inquire how the classes are distinguished from one another. To do this completely is by no means easy, and would occupy more space than can here be afforded. It must suffice to describe the leading distinctions.

§ 375. It is tolerably manifest that these distinctions cannot be originally given in the consciousness of the sequences themselves. By a nascent intelligence, the relation between two sensations that severally answer to some external cause and effect, cannot be known as essentially unlike that between two sensations that follow one another fortuitously. The two relations are two changes in consciousness, and nothing more. If, then, some changes, some sequences, are afterwards found to differ in nature from others, the difference must be in some collateral property disclosed by further experience. What is that property?

Comparison of a few cases will show us the answer to this question. After hearing in immediate succession two notes of different pitch, no difficulty is found in making those notes or rather, the ideas of them-pass through consciousness in the reverse order. After an ascending fifth has been struck on the piano, it is easy to represent the sounds so as to make a descending fifth: the two states of consciousness produced may readily be re-thought in inverted sequence. Not that the two states thus voluntarily changed in their order, are entirely like the original states. Though they are like in their natures they are widely unlike in their intensities. While the original states, which we know as two sensations of sound, are vivid, the two ideas which we find may be transposed are faint repetitions of them. And this it is which distinguishes one of these reversible sequences from a coexistence. If the successive states of consciousness A, B, can be made to occur in the opposite order B, A, without any diminution of vividness, the relation between them is what we know as coexistence. But if the states A, B, when they occur in opposite order,

can be made to do so only as the weak states B, A, the relation between them is that of reversible sequence. Thus much to prevent misapprehension. What it now concerns us to observe is, that there are sequences whose terms having been presented in one order, admit of being represented in the opposite order with great facility. Not that they occur in this opposite order with as much facility as in the original order. Two feelings that were experienced in a certain succession, tend, when recalled, to pass through consciousness in a like succession; and it is in virtue of their tendency to do this that we know them to have occurred in that succession; or rather, it is their recurrence in this succession which constitutes our knowledge of their original succession. But though, when uninterfered with, the represented feelings follow one another in an order. like that in which the presented ones followed; yet, in cases such as the one instanced, the slightest effort of volition reverses the order—an effort so slight as to be unaccompanied by any sense of tension. That some effort is required, may be inferred; since, while the represented impressions involuntarily follow one another in the original order, they do not follow in the opposite one, unless voluntarily. This, however, is the sole appreciable distinction. And these are the sequences which, objectively considered, we class as accidental.

If now, instead of two phenomena that have occurred in a fortuitous succession, or in a succession which to our ignorance seems fortuitous, we take two phenomena that have occurred in a certain order with considerable regularity, we shall find that the relation subsisting between the states of consciousness answering to them has a somewhat different quality. Instance the shouting to any one and the turning of his head. These two phenomena, frequently experienced in this order, have produced a mental connexion such that the occurrence of the one almost inevitably suggests an idea of the other. Moreover, the states of con

sciousness thus associated in experience have no tendency to occur in the opposite order. The turning of another person's head does not make us think of a shout. Nevertheless, there is little or no difficulty in reversing the order of these states. The thought of a person turning his head may be instantly followed by the thought of a shout, if we so will it. Sequences of this kind then, are distinguished by the peculiarity that though, when the antecedent is presented or represented, a representation of the consequent cannot without difficulty be prevented from rising in consciousness, yet these two states can readily have their order of succession changed. And this is the character of the sequences which, objectively considered, we class as probable.

When, however, we pass from non-necessary sequences to necessary sequences, we find not only that the states of consciousness are so connected that when the antecedent is presented it is impossible to prevent the consequent from following it, but also that the antecedent and consequent do not admit of transposition. As an illustration of the first peculiarity, may be taken our inability to think of a heavy weight as breaking the string by which it is suspended, without thinking of the weight as falling. And the last peculiarity is illustrated in the fact that the relation between a blow and an antecedent motion, cannot be represented to the mind in the reverse order.

§ 376. Thus the relation of sequence, considered subjectively as a change in consciousness, is of three general kinds. The fortuitous, in which the two terms are as nearly as may be alike in their tendency, or want of tendency, subsequently to suggest each other; and in which the change may be reversed in thought with a feeling of non-resistance like that with which it originally occurred. The probable, in which the terms are unlike in their tendency to suggest each other; but in which the usual

order of the terms may be inverted with but little effort. And the necessary, in which the antecedent being presented or represented to consciousness, the consequent cannot be prevented from following; and in which the direction of the change cannot be changed.

Leaving though it does much to be explained, this statement will serve to show that the classification of sequences is itself effected through other sequences. This classification, depending on the different modes in which the sequences comport themselves when tested, involves, at the outset, the ideas of like and unlike; while the process of testing them is itself an observing of the degrees of likeness or unlikeness between certain feelings they severally yield under experiment. And since the relations of likeness and unlikeness are the one a double sequence and the other a single sequence, it results that the classing of sequences implies the making them the terms of secondary sequences. As all relations are finally reducible to one, which is nothing else than a change in consciousness, it follows, even à priori, that all relations among the changes in consciousness must themselves be other changes.