The coherence and consistency of being was, it appeared in the last chapter, only to be maintained by assuming it to fall into two planes, or orders, always however relative to each other. The need of a measure forced itself upon even the superficial student. In the ordinary business of economical life one commodity of common use or of general acceptability steps into the place of a common measure. At first it is no more than one amongst many, a more suitable and convenient means of discharging the task of mensuration. But gradually it draws away into a world of its own, and acquires in common estimation a unique and peculiar dignity. It becomes a commodity of a higher order than the common, and is even treated as if it had intrinsic and inherent worth, apart from all relations of exchange. In a further stage it rises to rank as an invariable and almost supersensible standard, which amid all the fluctuations of currency tends to remain unchanged. One loses sight of the movement out of which it grew and in which it exists—the social give and take, the interaction of individual needs and general opinion.

The characteristic feature of this sphere of thought is the perpetual antithesis of terms. And its tragedy is the result of the tendency to separate the terms, and treat them as independently real. It matters not how often this error may be detected. Each side of the antithesis no doubt reflects itself upon the other. But we as constantly fail to note that reflection. Even the philosopher who most loudly preaches relativity falls into the common trap, and speaks of relatives as ultimate and absolute. He talks of an Unknowable, as if it could be without a Known (or Knowable): whereas no such term fully manifests itself. Each term owes its distinct existence to its correlative: each gives itself over to the other, and invests it with meaning and authority. Accordingly when even the ordinary mind, which takes these categories as they are given, is asked what each means, it can only reply by referring to the other. A cause is that which has an effect. The dialectic in the nature of thought,—its self-revising self-conscious nature—which was concealed in the First Part of Logic, where one term, when carried to its extreme, passed over into another, is made obvious in the Second Part, where each term postulates and even points to its correlative, and, however it may be contra-distinguished, cannot be thought without it. Thus, force is a meaningless abstraction without the correlative expression or utterance of force: and matter means nothing except in its distinction from, and yet reflection on, form. These, it may be said, are simple and tautological statements. They are principles, however, which every day sees disregarded. Have they, for example, been remembered by those theorists who tell us that everything is ultimately reducible to matter, or who propose to improve upon that theory by explaining that matter is after all only another name for force? Forgetting how this reduction is made, they are dealing with abstractions or mental figments, and losing their way in an endless maze of metaphysics. Do those who speak so confidently of laws of nature as something real and effective ever reflect that the two terms are more or less relative to each other, and that there is some latent metaphor in the phrase? Or if they prefer to speak of laws of phenomena, on which word is the accent to be laid? Those who thus speak of matter and force, really speak of a matter which is formed and form-possessed, capable of determining its own form, and of a force which can rule its own exertions: and for such conceptions the words in question are scarcely adequate representatives. They use the language of the Second, to express notions which properly belong to the Third branch of Logic.

The whole range of Essence or Relativity exhibits a sort of see-saw: while one term goes up in importance, the other term goes down. The several antitheses, too, have their day of fashion, and give place to others. Those inquirers who speak of the phenomena of nature shrug their shoulders at the very mention of essences: and the practical man, whose field is actuality, acquires a very pronounced contempt for both abstractions. One class of investigators glories in the perpetual discovery of differences, and stigmatises the seekers after identity and similarity as dreamers: while the latter retort, and name the specialisers empiricists. One intellect considers an action almost solely by its grounds or motives: another almost solely by its consequences. Some console themselves for their degradation by piquing themselves on what they might have been: others despise these 'would-be' minds for what they practically are. What a wealth there lies in each of us, which our nearest friends know nothing of, and which has never been made outward! But in this mode of thought, it is the persistent delusion, misleading science no less than metaphysics and the reflective thinking of ordinary life, to suppose that either of two relative terms has an existence and value of its own. In Germany paper-money is sometimes known as 'Schein' or Show. That term marks its relativity to the gold or silver currency of the realm: and it would be as absurd to pay with Austrian paper-money in Persia, as to take one term of Essence apart from its correlative. The disputes about essences, about matters and forces, about substance, about freedom and necessity, or cause and effect, are generally aggravated by a forced abstraction of one term from another on which its meaning and existence depend.

The essence may be roughly defined as that measure or standard which corresponds to the variation of immediate being, and yet remains identical in all variation. Or, if we like, we may say that this immediate being, which, as derivative, may now be called existence[1], has its ground in the essence. The essence is the ground of existence: and essence which exists is a 'thing,' Such an existing essence or thing subsists in its properties; and these properties are only found in the thing. Thus the essence, when it comes into existence as a thing, turns out to be a mere phenomenon or appearance.—Such briefly stated is the development of essence proper into appearance.

With the idea of essential being—a permanent which yet changes, there emerge the problems connected with the double aspect of relation as identity and difference,—the favourite categories of reflection. These terms indeed the popular logician would fain avoid as savouring of pedantic accuracy, and prefers the psychological titles of similarity and contrast. These, he tends to insinuate, are unique experiences, direct feelings, beyond which it is impossible to go in analysis. The logician, on the other hand, must insist on dealing with the more radical phase of the terms. And he must note their essential interdependence and their intrinsic contradictoriness. Abstract sameness, or sameness which does not presuppose a tinge of difference, is a fiction of weak thought, which wishes to simplify the subtlety of nature. Identity is a relative term, and for that very reason presupposes difference: and for the same reason difference presupposes identity and is meaningless without it. The whole dispute about 'Personal Identity,' as it descends from one English psychologist to another, is enveloped in the obscurity which springs from failure to grasp the logical antinomy on which the question turns. When I feel that my friend whom I have not met for years is still the same, should I take the trouble to express myself in this manner, unless with reference to the difference betwixt Then and Now? If I remark that two men are different, would the remark be worth making or hearing unless there was some identity which made that difference all the more striking? The essence is, in short, the unity of sameness and difference: and when so apprehended, it is the ground by which we explain existence. The essence, ground, or possibility, is at once itself and not itself: if it is self-identical, it is for the same reason self-distinguishing. If it is to be itself, it can only be so by negativing what in it is other than itself. The affirmation of self implies the negation of the other of self,—the redintegration (though not the blank absorption) of the other in it. This is the crux which lies in Ex nihilo nihil fit: what exists must not be other than the essence (the effect not more than the cause), and yet unless it is other and different, there has been no passage from essence to existence.

The tendency to identify, and the tendency to distinguish, alternate both in scientific thought and in general culture. But whichever prevail for the moment, it is only as a re-action and a protest against the one-sided predominance of the other. And thus both ultimately rest upon and presuppose a ground of existence which is neither mere sameness nor mere difference. It is only when the two tendencies meet and interpenetrate that science accomplishes its end, and discovers the ground of existence. In the first instance the world presents to incipient science the aspect of mere identity and of mere difference. Likeness is confounded with sameness, and unlikeness with diversity. The popular and the infant minds do not draw fine distinctions. Things to them are either the same or different: one point of sameness may in certain conditions obliterate whole breadths of difference; and tiny divergence may make as nothing all the many points of agreement, purely and simply, i. e. abstractly. But the process of comparison, setting things beside each other, teaches us to refine a little, and speak of things as Like or Unlike. One thing is like another when the element of identity preponderates: it is unlike, when the difference is uppermost. Thus while we distinguish things from one another, we connect them. From mere variety, and mere sameness, we have risen, secondly, to distinctions of like and unlike. But, thirdly, this distinction of same and different is in the thing itself. Everything includes an antithesis or contradiction in it: it is at once positive and negative. One can only be virtuous, so long as one is not utterly virtuous.[2] To be a philosopher, implies that you are not wholly or merely a philosopher. The rational animal is so, because of an inherent irrationality, and is so, only as rising upon and superseding it. Every epithet, so to speak, by which you describe any reality, presupposes in it the negative of the quality. Not only does every negation presuppose an attempted or surmised affirmation, but an affirmation is always, it may be said, a re-affirmation against an incipient doubt. Every stage of reality involves the presence of antithetical but inseparable elements: every light implies a shadow to set it forth. The epithet of each real is only a potiori. While it retains itself, it must lose itself. Its positivity is only secured by its self-negation and its identity is based upon its self-distinction. Every proposition which conveys real knowledge is a statement that self-sameness is combined with difference. Every such proposition is synthetical: it unites or identifies what is supposed to be implicitly different, or differentiates what seemed only identical. Here we have that coincidentia oppositorum, which is the truth of essence. Thus, e. g. the essence of the Self is the contradiction between its self-centred unity and its existence by self-differentiation into elements.

Essence, thus comprehended as the unity of identity and difference, as that which is and is not the same, is the Ground, from which an Existence comes as the Consequent. Or, otherwise expressed, the ground is the source of the differences,—the point where they converge into unity, and whence they diverge into existence. Everything in existence has such a ground: or, as it is somewhat tautologically stated in the common formula, a sufficient ground. On that account, it is no great matter to give reasons or grounds for a thing, and no amount of them can render a thing either right or wrong, unless in reference to some given and supposedly fixed point. For the ground only states the same thing over again in a mediate or reflected form. It carries back the actual fact to its antecedent: and thus deprives it of its abruptness or inexplicability, by showing you it was there implicitly; and therefore as you accepted the ground you cannot complain of what but serves to continue it. To refer to the ground is to say there is really nothing new: and as you raised no objection before, you need raise none now.

The Existent world—a world of existents, each conditioning and conditioned—is popularly described as a world of Things. These Things are the solid hinges on which turns our ordinary conception of change and action. They act, and exhibit properties. Being is partly substantive, partly adjective. The Thing itself is the ground of its properties: i. e. each thing is looked upon as a unity in which different relations converge, or an identity which subsists through its changing states. This is the side emphasised in ordinary life, when a thing is regarded as the permanent and enduring subject, which has certain properties. But a little science or a little reflection soon turns the tables upon the thing, and shows that the properties are independent matters, which, temporarily it may be, converge or combine into a factitious unity which we term a thing. But these very matters cannot be independent or whole, just because they interpenetrate each other in the thing. The thing, which from one point of view seemed permanent, and the properties, which from another point of view seemed self-subsistent matters, are neither of them more than appearance. For they must be at one, and at one they cannot be. And if we reduce the various matters to one, and speak of Matter in general, we have a mere abstraction—a something which only becomes real by being stamped with a special form. Mere Matter like mere Thing (thing in itself) is a knowable Unknowable.

In this way we pass from the talk about essence, things, and matter into an other range of the sphere of relativity. We no longer have one order of being behind or in the depth, and another referring back to it. We now speak (as Mill does) of Phenomena:—not phenomena of an unknown, but, simply disregarding the background, we find all we want upon the surface. For neither is thing more real than property, nor essence than existence. Each is exactly equal in reality to the other, and that reality is its relation to the other. The thing and the essence with their claim to truth disappear. Nothing truly is: but only appears to be. The semblance (Schein) may refer to an essential. But the appearance (Erscheinung) only refers to another appearance, and so on. The phenomenal world is all on one level:—as was the world of immediate being. But, there, each term of being presented itself as independent: here, nothing is independent—nothing ever really is, but only represents something else, which is in its turn representative. Yet even here there is a pretence of hierarchy in existence. In the phenomenon a certain superiority is attributed to its Law. But the conception of Law is hard to keep in its proper place. Either it assumes a permanency—even were it but a permanent possibility—as contrasted with the coming and passing phenomenon: and then it is apt to be confounded with a real Essence. Or, on the other hand, it comes to be looked on as a mere way of colligating phenomena,—as a mere appearance in the variety of appearance (as it were an iris in the rain-drops)—a phenomenon of a phenomenon. Such a distinction between the phenomenon and its law; therefore, is and must be illusory, or itself only an appearance. As such it is described as the difference of Form and Content: two terms, which are incessantly opposed, but which more than most antitheses reveal when pressed the hollowness of their opposition. For true or developed Form is Content, and vice versa.

Instead however of this practical identification of the law of the phenomenon with the duly-formulated phenomenon itself, it is more natural to emphasise the discordance of the two aspects of reality, and yet to acknowledge their essential relativity. This essential relativity in the phenomenon has a threefold aspect: the relation of whole and parts; of force and the exertion of force; of inward and outward. The relation of whole and parts tends to explain by statical composition: the relation of force and its exertion, by dynamical construction. According to the former the parts are constituted by their dependence upon and in the whole, and yet the whole is composed by the addition of the several parts together. Each extreme is what it is only through the other. Only those parts can make up a whole, which somehow have the whole in them: and to become the whole, they must contrive to wholly obliterate their partitional character. A better exhibition of the inner unity and the difference between form and contents is seen in the relation of a force to its exertion. Here the contents appear under a double form: first, under the form of mere identity, as force,—secondly, under the form of mere distinction, as the manifestation of that force. Yet a force is only such in its utterance or manifestation, while in that utterance, if abstracted from the force it carries forth, all energy has been superseded. This separation of content and form, or of content as developed in two forms, appears still more clearly in the third relation: that of outward and inward. This is a popular distinction of very wide application in reference to phenomena. But neither outside nor inside is anything apart from its correlative. If the elements implied in the conception of phenomena are to have full justice done them, it must be expanded so as to give expression to these two phases, to include the outward and the inward. But at first only by reverting to something like the old distinction of essence and existence,—an essence however which is existent or phenomenal, and an existence which stands independent, though in correlation. Such being is Actuality—being, i. e. which is what it must be, and must be what it is.