Edward Caird's Hegel



DURING the long mental struggle, the history of which has been outlined in the last chapter, Hegel had in the main lived for himself, without any attempt to communicate his thoughts to the world. "When he visited his family at Stuttgart, on his way from Switzerland to Frankfort, his sister found that he had become silent and self-absorbed; and about the same time Schelling wrote to reproach him with yielding to a kind of irresolution and dejection of spirit that was unworthy of him. A depressed, melancholic, almost sentimental tone, unusual with Hegel, runs through the somewhat ill-constructed verses-he had not a good ear for meter- specimens of which his biographer has published. The only literary work which he prepared for the press during the Frankfort period, was an essay on the reforms in the constitution of his native Wurtemberg, the necessity of which had been made evident by the rough pressure of France, and even this was not published. In philosophical matters, the conflict of opposing thoughts and sympathies of which he was not yet master kept him silent.

But now, in the year 1800, when he had at last grasped the leading idea of his system, and had commenced to work out its application with some degree of systematic fullness, he began to long for an opportunity of expressing himself, and of comparing his thoughts with those of others. In this view he reopened communication with Schelling, with whom his correspondence had apparently dropped for some years, and informed his friend that he was prepared, or rather that he was almost prepared, to take his share in the philosophical battle. Hegel's father had died in the beginning of 1799, and the small sum of about 300 pounds which he had received as his share of the family inheritance, made him for a time independent of the work of teaching.

Accordingly, in his letter to Schelling, he begs him to recommend some economical place of residence, he would prefer a Catholic city, in order to have a nearer view of that religion, where he could live cheaply (with, as he specially states, the advantage of ein gutes Bier), enjoy some good society, and gather himself together before entering into the literary and philosophical hubbub of Jena. He has, he declares, watched Schelling's great public career "with admiration and joy," but wishes Schelling to know that he himself also has been in silence making his way to a philosophical view of things.

"In my scientific education, which began with the endeavor to satisfy humbler wants, I have been driven onward to philosophy, and the ideal of youth has thus, of necessity, had to take on the form of reflection, and transform itself into a system. Now, while I am still employed with this task, I begin to ask myself where I can find a point of contact to bring my thoughts to bear upon human life. Of all the men I see around me, you are the one in whom I should most desire to find a friend, as in other things, so especially in reference to this business of getting myself expressed, and brought into effective contact with the world; for I see that you have apprehended man as he is-i.e., with a comprehensive sympathy which is unstained by vanity. I therefore can look to you with the full confidence that you will be able to recognize my disinterested endeavors, and to find a value in them." (Hegel letter to Schelling)


In this appeal to Schelling there is traceable a wish on Hegel's part to indicate to his friend that he is substantially, though only substantially, at one with him, and that though for this reason he can hope to co-operate with Schelling, yet that the philosophical form which his thoughts have taken has grown by an independent process out of the needs of his own spirit When we consider how Hellenic art and life had been to Hegel the first key to the spiritual significance of things, how the idea of organic unity derived from that source had gradually transformed itself under the influence of philosophical criticism, and how, finally, by the aid of the idea of spirit, it had been applied, not merely to the State, but to the world as a whole,-the special words of this announcement will seem significant and characteristic. The answer of Schelling is not preserved; but the result was that Hegel gave up the idea of a preliminary retreat to Bamberg or any other city, and resorted at once, in January 1801, to Jena, to take his place beside Schelling as a champion of "the philosophy of Identity."

In July of the same year appeared his first published work, 'On the Difference between the Systems of Fichte and Schelling,' in which Hegel appears as in all essential points a defender of the latter against the former. The dissertation 'De orbitis planetarmn,' which he published immediately afterwards, pro licentia docendi, and which was written very much in the spirit of Schelling's Philosophy of Nature, though on a subject which Schelling had never discussed, confirmed the idea of Hegel's complete agreement with Schelling; and he had soon after to contradict the statement of a newspaper that he was a fellow-Wurtemberger whom Schelling had brought forward under his wing, to be a special pleader in his behalf. But though asserting his own independence with decision and almost with violence, Hegel was at this time quite willing to accept the place of a defender of the philosophy of Identity; and in 1802 he united with Schelling in the publication of a 'Critical Journal,' in which the contributions of the two writers were not in any way distinguished from each other-a circumstance which, after Hegel's death, led to some controversy about the authorship of several of the pieces.


The common point of view which is expressed in this Journal, as well as in Hegel's treatise and Schelling's successive works of this period, is, as has been said, that of the so-called "Philosophy of Identity." This may be better understood if we remember to what it was opposed. It was opposed, on the one hand, to that common-sense dualism for which mind and matter, or subject and object, are two things absolutely independent of each other-two things which, if brought into relation at all, can only be externally harmonized, like the two clocks of Leibnitz, but between which no kindred nature or principle of unity can be discovered. In like manner, it was opposed to the Kantian and the Fichtean philosophy of subjectivity, which, indeed, had expressed the idea of a unity beyond difference-a unity of subject and object, perception and thought-but which had not fully developed that idea, or had developed it only in a partial and subjective way. Thus, in the Kantian philosophy, only the phenomenal object was supposed to be knowable, while the real object was treated as a thing-in-itself-i.e., a thing not essentially related to, or knowable by, the subject; and, on the other hand, the subject was regarded as incapable of reaching beyond his own sensations and impulses-beyond the circle of his own inner life, so as to know or to act on anything but himself.

In the Fichtean philosophy, again, the independent existence of things in themselves, outside of the circle of subjective phenomena, was denied; and the non-ego was reduced to a negative condition, through which the ego realizes its own life of self-determination: nay, even this negative condition, the ego, by an incomprehensible act, was supposed to produce for, and out of, itself. But the effect of this theory of Fichte was not to idealize the object, but rather to explain it away, and to confine the ego to a mere inward struggle with itself, in which it could never go beyond itself in a real self-surrender, and therefore could never return to itself with the fruit of a real liberty. The non-ego was thus reduced by Fichte to a specter: but, in spite of that, or just because of that, it could never be vanquished or spiritualized. If it ceased to exist as an outward object, it was only to reappear as an incomprehensible opposition of the mind to itself.

Schelling made the first step out of this charmed circle of subjectivity, when he endeavored to show that in nature there is the same movement of antagonism and reconciliation as in spirit: in other words, that nature also has in it a dualism corresponding to the dualism of self and not-self in consciousness, and that therefore it is one principle which we find manifested in mind and matter alike. To Fichte's declaration that "the I is everything," he adds, therefore, the converse that "everything is I", i.e., that nature is no unreal shadow of the movement of subjective thought, but has manifested in it the very principle which constitutes the ego in man. Hence, as Schelling expressed it - and Hegel for a time made no objection to the expression-there are no qualitative, but only quantitative, differences in things. Each of the two opposites, mind and matter, is in itself a subject-object, and contains and reconciles in itself the opposition of an ideal and a real element. And the same is true of every separable form, whether of mind or matter; so that, from the point of view of the absolute, everything that exists is an identity of subject and object, and all these identities are essentially one.


The essential principle, then, in which Hegel and Schelling meet together, is that there is a unity which is above all differences, which maintains itself through all differences, and in reference to which all differences must be explained. They agree also in calling this unity spiritual, and in asserting it as the articulus stantis vel cadentis philosophise-the point of view at which all true philosophy must place itself in order to understand the world. The program of the 'Critical Journal' asserts, therefore, that " the great immediate interest of philosophy is to put God again absolutely at the head of the system as the one ground of all, the principium essendi et cognoscendi, after He has been for a long time placed, either as one finitude alongside of other finitudes, or at the end of them all as a postulate,-which necessarily implies the absoluteness of the finite."

In other words, philosophy has hitherto started with some fixed opposition, such as those of subject and object, of mind and matter, of freedom and necessity, forgetting that these oppositions could not be intelligible except on the presupposition of a unity that transcends them. Now this presupposed unity, "just because it is presupposed, is not present to the ordinary consciousness, which, therefore, always thinks of the object as essentially different from the subject." It is an unconsciously assumed basis of consciousness, which philosophy brings to light, and by aid of which it transforms our ordinary view of the world. Hence, also, skepticism performs a valuable service to philosophy, in that it confuses and destroys the distinctions of the ordinary consciousness, or exhibits their relative and limited character.

Thus, when the popular consciousness (or the common-sense philosophy which makes itself the spokesman of that consciousness), asserts that the object and the subject of knowledge are essentially distinct, skepticism points out that knowledge, as involving their relation to each other, is inconsistent with such distinctness. In other words, skepticism proves, on the hypothesis of the distinction of subject and object, that knowledge is impossible. But the true conclusion from this argument is, that the object is not absolutely distinct from the subject that knows it, but in its distinctness is yet essentially related to, and so one with, it. The negative dialectic of the skeptic, therefore, proves only that each limited idea contains its own negation, and thus carries us back to that identity which is presupposed in all distinction, and in the light of which each distinction is reduced to its proper meaning and value, as a manifestation or expression of the unity.

To Schelling and Hegel it appeared that this idea of the unity beyond all differences was the new inspiring principle which was to liberate science and life from the bonds of abstraction in which they had been hitherto held. The Cartesian dualism, with its abstract opposition of mind to matter, had, they asserted, only given philosophical expression to the principle of an all-embracing dualism, which was already manifesting itself in the political and religious life of Europe in the breaking up of the old feudal and Catholic system. On this principle of division, and therefore of death, all the sciences had been based, and they had therefore been built up into "a temple of the understanding which reason had deserted."

Now at last the literature of the time was beginning to show a weariness of this shallow expansion, this accumulation of dead facts, to which the spiritual bond was wanting. A longing had been awakened, as it were " a thirst of Dives for a drop of fire "-a curious metaphor-" for a concentration of living intuition," which might destroy the divisions of reflection, and reveal again the organic unity of the world. It was the business of the philosophical critics to assist in the development of this new consciousness, to carry on vigorously the war against the dualistic dogmatism and skepticism of common-sense, to recognize and appreciate every manifestation, however imperfect, of the great idea of Identity or Unity, and to disentangle it from the imperfections of its expression.


In the former point of view, the Journal proposes to carry fire and sword into the quarters of writers like Schuiz, Krug, and even Reinhold, who held by the fixed oppositions of the finite as if they were absolute; in the latter point of view, it proposes to apply a discriminating criticism to the mystics-"the beautiful souls"-who had apprehended "the pure idea of philosophy" without being able to give it scientific expression, and also to the theories of Kant, Fichte, and their followers, in which that idea was present, though in a one-sided and still preponderantly subjective form. For these philosophers, just because of their leaning to the subjective as opposed to the objective, had " not broken through to pure formlessness, or, what is the same thing, to the absolute form;" i.e., they had not, by equal negation of all differences, reached the unity in which all distinction and differentiation begin, the universal point of view from which alone particulars can be truly estimated and understood.

The articles in the Journal were unsigned, to indicate the unity of spirit in. the authors; but it was mainly by Hegel that this program, especially the latter part of it, was carried out, even if we give Schelling the benefit of the doubt in all cases in which the authorship of the different pieces is uncertain. Schelling, indeed, soon directed his main literary activity to a new 'Journal for Speculative Physics,' which he established, leaving the work of the 'Critical Journal' to Hegel. Schelling's removal from Jena in the summer of 1803, which put an end to the intimate alliance of the two friends, may have had something to do with the cessation of the latter Journal. It is, however, clear, that closely as they were associated in their polemical work, Schelling and Hegel were certain to diverge from each. other as soon as an advance was made to a positive definition and evolution of the principle of "identity." And this divergence is already manifested in the essay which constitutes the last number of the Journal, in which Hegel retracts the admission of the equality of nature and spirit made in his first treatise, and asserts that, as the absolute unity or identity is spiritual, so spirit "over-reaches" nature, or includes it as a factor in its own life. [Ed. note - "over-reach" is the essence of "to grasp" or the Concept (Begriff).]

The truth is, that the 'Critical Journal' indicates a point of coincidence between two minds that were advancing in somewhat different directions. Schelling, on his side, had never quite freed himself from the Fichtean idea, according to which the ego and the non-ego, or the two factors that correspond to them in nature, are fundamentally irreconcilable. Hence, when he spoke of the absolute as the identity in which all such difference and opposition is transcended, he was not able to think of it as still leaving room for the play of difference, but was inclined rather to conceive it as an absolute oneness, in which all division and distinction is submerged and lost.

In this spirit he declared that the finite is explicable only from itself, but not from the infinite, and spoke of the organ of philosophy as an "intellectual intuition," analogous to the sensuous intuition of the artist, but entirely opposed to "reflection," i.e., to all thought which moves by reasoning from part to part, and does not grasp the whole at once in one comprehensive glance of genius. While, therefore, he agreed with Hegel in calling the unity spiritual, and in conceiving it as a unity of subject and object, of knowing and being, yet he emphasized the unity at the expense of the difference, and had much more success in showing that they all disappear in it, than that it can in any way reproduce them from itself. And when he proceeded to develop his system, he seemed externally to take up again the finite elements he had rejected, rather than to develop them with a new meaning from the principle. His unity, therefore, as Hegel afterwards said, was a unity of "substance" rather than of spirit; or if it was nominally spiritual, yet the idea of spirit, if it be left undifferentiated and undeveloped, is little more than the idea of substance.


Now it is observable that in all these respects Hegel distinguished himself from Schelling even at the time when they were most closely allied. In the treatise "On the Difference of the Fichtean and Schellingian Systems," he insists that the identity of philosophy is not an abstract identity as opposed to difference, but a spiritual unity which differentiates itself, that through opposition and conflict it may reach a higher unity. "The necessary diremption is one factor of the life which forms itself by eternal opposition; and the totality, which is in the highest sense vital or organic, is produced only by restoration out of the most extreme division." Hence the true "intellectual intuition" is not an immediate apprehension of truth which is exclusive of the process of reflection, but includes that process in itself.

At the same time, Hegel still holds with Schelling that the movement of reflection outside of philosophy is quite different from its movement within it; and that the highest result to be achieved by the former is the felo de se of skepticism, i.e., to carry up the finite categories to self-contradiction, and so negatively prepare the way for the intuition of the absolute identity. Philosophy, therefore, in spite of its negative introduction, is regarded as starting, in Spinozistic fashion, with the absolute. "As an objective totality, knowledge furnishes the reason or ground for itself, and its parts are grounded at the same time as the whole. It is thus a whole which has no more need of a special handle in the way of an external reason through which it may be proved, than the earth needs a special handle to be grasped by the force that carries it round the sun."

Hence Hegel is very severe in his criticism of Reinhold, who would begin by hypothetically assuming some relative point of view, and making his way from it to the principle of philosophy. On the contrary, argues Hegel, there is no way from the finite to the infinite; we can only reach the latter if we deny and cast loose from the former. The only way to get entrance into philosophy is to throw in one's self headlong "a corps perdu hineinsusturzen." Reinhold's philosophy, just because it begins with preliminaries outside of philosophy, never gets beyond preliminaries-"the whole of his force is wasted in the run, and nothing is left for the leap." In an amusing squib, written against Reinhold, Schelling refers to this criticism upon hypothetical philosophy, and speaks of Hegel as "a downright categorical kind of being, who tolerates no ceremony with philosophy, but, without waiting for any such grace before meat, falls to at once with a good appetite."


It is, however, just at this point that we find one of the germs of division between Hegel and Schelling. Hegel's denial of the need of an introduction to philosophy is ambiguous, for the negative propadeutic of skeptical reflection which he admits is still an introduction. Reinhold's real fault was not that he started with the finite, and made his way from it to the infinite, but that he did not see that it is through the negation of the former that we reach the latter. It is because the finite-if we take it as an absolute independent existence-contradicts itself, that we are driven back upon the infinite. On the other hand, this process is not purely negative, but has in it a positive element which Schelling, and Hegel also at this time, seemed to neglect It is not simply that, by the self-negation of the finite, room is made for the intuitive genius of the philosopher to grasp the infinite.

The negative attitude toward the finite involves in itself an inchoate consciousness of the infinite; "we are near awaking when we dream that we dream." Or, to put the matter in a different point of view, the ordinary consciousness, because it is in its way a thinking consciousness, carries in itself the means of its own correction; and philosophy, in refuting and transforming it, is yet bound to pay it due respect as a thinking consciousness, and to refute it out of its own mouth. If the philosopher does otherwise, -if he assumes prophetic airs, or speaks to ordinary men from the height of an "immediate insight" or "transcendental intuition," from which they are excluded,-he, as Hegel soon began to assert, is pretending "to be of a different species from other men," and is "trampling the roots of humanity under foot." Besides, in doing so he is actually abandoning his highest claim, which consists simply in this, that he is not speaking like an artist to those who have some special natural gift or taste, but is interpreting that universal consciousness which is in all rational beings as such, and which, therefore, all are capable of recognizing.

"If philosophy requires of the individual that he should lift himself into the pure ether of thought, on the other hand the individual has a right to demand of philosophy that it should let down a ladder on which he may ascend to this point of view; nay, that it should show him that he has already this ladder in his own possession. This right is founded upon the absolute independence which, in every form of consciousness, be its content what it may, a rational being knows himself to possess; for in every such form there is involved the immediate certitude of self-consciousness - a consciousness which is not conditioned by anything out of itself." (Hegel) In other words, a rational being, because he is rational, has a right to demand that the highest truth shall be presented to him not as a revelation of something foreign and strange, but as the explanation of that which already he is conscious of being.

The mistake of Schelling, in absolutely opposing philosophy to the reflective thought of the finite consciousness, had another bad effect. It produced a neglect of method in philosophy itself. Relying on "intellectual intuition," and seeing in everything the manifestation of one principle, Schelling and his followers represented the world as a series of "potencies" of the absolute; but in doing so, they rather externally fitted the threefold schema of Kant to the given matter of the sciences, than developed the particulars out of the general principle. At most they moved by vague analogies, by poetic leaps and bounds, rather than by any definite process or evolution of thought. They did not do sufficient justice to the different elements of experience really to overcome their differences, and bring them back to unity.

While, therefore, their negative dialectic simply blotted out all the difference of finite things, and merged them in the absolute, their positive dialectic, if it could be called dialectic, was a series of superficial analogies, or, at best, happy guesses, which might be guided by a true idea, but which did not really bring that idea into living contact with the special characteristics of each sphere of reality. Hegel sought to reform this arbitrary procedure by introducing a strict dialectical evolution of thought. And the first step towards this was to show that the negative, distinguishing, or differentiating movement of thought is essentially related to, or rather an essential part of, its positive, constructive, or synthetic movement. On the one hand, therefore, he points out that in the negative movement of thought, by which the finite consciousness is shown to be in itself contradictory and suicidal, there is already involved a positive apprehension of that which is beyond the finite; for, as the negative is a definite negative, it includes that which is denied and something more, - and this something more is already, or at least implicitly involves, the idea that solves the contradiction.

On the other hand, and for the same reason, the positive idea-the idea of the infinite which is reached by negation of the finite - cannot be taken as merely affirmative or positive; it contains in itself an essential reference to the finite by negation of which it was reached. We must not, therefore, treat it like Spinoza, as a mere terminus ad quern-a lion's den, in which all the tracks of thought terminate, while none are seen to emerge from it. The infinite would have no meaning for us, it would he a thought without reality, if it were not itself the finite seen sub specie aeternitaetis. The mystic intuition of "all things in God" is a dream, unless it can unfold its concentrated white light into new views of the many forms of nature and human life, with all the varied and definite hues and shapes. "Am farbigen Abglanz haben wir das Leben." A theory of the world as spiritual must face or overcome the opposition of spirit and nature; it must not simply escape from the contradiction of life into the "pure ether" of thought, but must go down into the contradiction and explain it. It must, indeed, conceive the world as a unity, but it must reach this unity by a patient exhaustion of those differences and oppositions which seem to make unity absurd and impossible. Hence the negative dialectic of skepticism will find full play, not merely before philosophy as an introduction, but within it as the means of its evolution.


Connected with this, finally, is Hegel's more definite assertion, which, as we have seen, was already made in the last number of the 'Critical Journal,' that the unity to which all things must be brought is not some middle term between nature and spirit-some identity in which that, like all other distinctions, is lost; but that it is the unity of spirit with itself, as subordinating and including in itself that very nature which seems its absolute opposite. Only by this idea can we reconcile the freedom of man - in the sense that what determines him is his own nature, and that alone - with his relations to that which is not himself, to the external world, and to other rational beings.

The life of spirit and nature is indeed ultimately one; "the infinite expansion of nature, and absolute retraction of the ego upon itself, are fundamentally identical; yet both being equally real, spirit is higher than nature. For though in nature we have the realization, the infinitely diversified mediation and evolution of the absolute, yet spirit, as being essentially self-conscious, when it draws back the universe into itself as it does in knowledge, at once includes in itself the outwardly expanded totality of this manifold world, and at the same time overreaches and idealizes it, taking away its externality to itself and to the mind, and reflecting it all into the unity of thought."1 In other words, nature is to be regarded not as another existence side by side with mind, but as part of its own life; for though at the lower point of view the two may appear as irreconcilable opposites, at the highest point the life of nature is seen to be but an element in the life of spirit.

The development of these different points of opposition between Hegel and Schelling is the main fact of the philosophical life of the former during the years 1803-6 - years in which Hegel continued to teach, at first as a privat docent, and, after the beginning of the year 1805, as an extraordinary professor in the University of Jena. During this period Schelling was showing a continually increasing bias towards theosophy and mysticism, and some of his followers, by their exaggeration of his arbitrary methods, were bringing the philosophy of nature into discredit. All this tended to repel Hegel more and more from a line of speculation which seemed to produce nothing but continual reiterations of the principle of identity, or, if it went beyond this, fell into wayward and fanciful constructions - hybrids between poetry and philosophy with the distinctive merits of neither.


Accordingly, in his Jena lectures we find him insisting with even greater emphasis on the necessity of method, of clear consciousness as to the meaning and value of the categories employed in philosophy, and of a strict logical advance from step to step, so that each thought shall be evolved by distinct dialectic from that which precedes. In the same spirit he insisted, as has been before indicated, on the duty of meeting the ordinary consciousness on its own ground, and of showing from its own premises the necessity of advancing to the philosophical point of view: and it was to supply such an introduction to philosophy that he wrote his first important work, the 'Phenomenology of Spirit'.

In this book Hegel gives us a kind of genetic psychology or philosophical 'Pilgrim's Progress,' in which the individual, beginning with the lowest sensuous consciousness which is possible to a rational being, is gradually led upwards, by the dialectic of his own thought, to the highest speculative idea of the world as an organic system, whose principle of unity lies in the self-conscious intelligence. The preface to the 'Phenomenology' is specially important as a landmark in the development of Hegel, because it is in it that he first decisively breaks with the school and method-or rather want of method-of Schelling, whom, however, he never names. Indeed it is, perhaps, not so much Schelling himself who is aimed at, as the general tendency-of which he was the least guilty though the most prominent representative, the tendency, viz., to make intellectual intuition or immediate feeling, even when conceived as the gift of certain privileged natures, the organ of philosophy.

In opposition to this tendency, Hegel points out the need for mediation or logical development of thought, both to bring men to the true principle of philosophy, and to develop it to a system. In reference to the former, he contends, in language which has already been quoted, that no one has a right to speak as if he had a vision of truth of which other men were incapable, since philosophy must prove its claims by meeting every one on his own ground. In reference to the latter, he argues that no one can be said really to possess a principle unless he can develop it to its consequences. "The principle of philosophy, even if it be truly apprehended, is turned to falsehood if it is taken only as a principle." "Everything depends upon the absolute truth being apprehended, not merely as substance but as subject"-i.e., not as a Spinozistic identity, in which all difference is lost, but as a spiritual principle. But as such a principle it can be apprehended, only if it is seen to manifest itself in and to transcend all differences, and especially the difference of subject and object, man and nature- only, in short, if it is recognized as the principle of a system. For apart from such evolution to a system, the mere name of spirit or subject cannot mean much more than substance. Schelling's undeveloped spiritualism, just because it is undeveloped, is little more than Spinozism.

The 'Phenomenology' is, in a literary point of view, the most perfect of Hegel's works. It wants, indeed, the clearness, the dialectical precision, and the just proportion of parts which we find in some of his later writings; but it compensates for this by a certain imaginative richness and power of utterance, a certain fervid fluency, as of a thought which, after long brooding, had at last burst into expression. The peculiar merit of the book is not merely that its dialectical process is assisted in its expression by imagination, but that the process itself seems to become poetical and imaginative through its success in overcoming the abstractions and reconciling the oppositions with which it deals. It is not poetical philosophy; it is philosophy in its last synthesis showing itself to be poetry, thought taking fire by the rapidity and intensity of its own movement. Hegel called it his " voyage of discovery;" and it is indeed a sort of philosopher's autobiography, in which all the main forces that influenced his own development are clearly indicated. It contains the system in its first conception, when it had not yet been thoroughly objectified, or when the philosopher had not yet attempted to ascertain his own " personal equation," and allow for it: but, for that very reason, it has a special value for every one who wishes to study the genesis of the system.