No essential corrections and additions, such as might modify the fundamental thoughts of the work, will be found in this new edition, which simply contains corrections, amplifications, and corroborations, many of them interesting and important. Let me take only a single instance: § 21, on the "Intellectual Nature of Empirical Perception." As Schopenhauer attached great importance to his proof of the intellectual nature of perception, nay, believed he had made a new discovery by it, he also worked out with special predilection all that tended to support, confirm, and strengthen it. Thus we find him in this § 21 quoting an interesting fact he had himself observed in 1815; then the instances of Caspar Hauser and others (taken from Franz's book, "The Eye," &c. &c.); and again the case of Joseph Kleinhaus, the blind sculptor; and finally, the physiological confirmations he has found in Flourens' "De la vie et de l'intelligence des Animaux." An observation, too, concerning the value of Arithmetic for the comprehension of physical processes, which is inserted into this same paragraph, will be found very remarkable, and may be particularly recommended to those who are inclined to set too high a value on calculation.
Many interesting and important additions will be found in the other paragraphs also.
One thing I could have wished to see left out of this Third Edition: his effusions against the "professors of philosophy." In a conversation with Schopenhauer in the year 1847, when he told me how he intended to "chastise the professors of philosophy,"[6] I expressed my dissent on this point; for even in the Second Edition these passages had interrupted the measured progress of objective inquiry. At that time, however, he was not to be persuaded to strike them out; so they were left to be again included in this Third Edition, where the reader will accordingly once more find them, although times have changed since then.
Upon another point, more nearly touching the real issue, I had a controversy with Schopenhauer in the year 1852. In arguing against Fichte's derivation of the Non-Ego from the Ego in his chief work,[7] he had said:—
"Just as if Kant had never existed, the Principle of Sufficient Reason still remains with Fichte what it was with all the Schoolmen, an œterna veritas: that is to say, just as the Gods of the ancients were still ruled over by eternal Destiny, so was the God of the Schoolmen still ruled over by these œterna veritates, i.e., by the metaphysical, mathematical, and metalogical truths, and even, according to some, by the validity of the moral law. These veritates alone were unconditioned by anything, and God, as well as the world, existed through their necessity. Thus with Fichte the Ego, according to the Principle of Sufficient Reason, is the reason of the world or of the Non-Ego, of the Object, which is the product or result of the Ego itself. He took good care, therefore, neither to examine nor to check the Principle of Sufficient Reason any farther. But if I had to indicate the particular form of this principle by which Fichte was guided in making the Ego spin the Non-Ego out of itself, as the spider its web, I should point to the Principle of the Sufficient Reason of Being in Space; for nothing but a reference to this principle gives any sort of sense or meaning to his laboured deductions of the way in which the Ego produces and manufactures the Non-Ego out of itself, which form the contents of the most senseless and—simply on this account—most tiresome book ever written. The only interest this Fichteian philosophy has for us at all—otherwise it would not be worth mentioning—lies in its being the tardy appearance of the real antithesis to ancient Materialism, which was the most consistent starting from the Object, just as Fichte's philosophy was the most consistent starting from the Subject. As Materialism overlooked the fact, that with the simplest Object it forthwith posited the Subject also; so Fichte not only overlooked the fact, that with the Subject (whatever name he might choose to give it) he had already posited the Object also, because no Subject can be thought without it; he likewise overlooked the fact, that all derivation à priori, nay, all demonstration whatsoever, rests upon a necessity, and that all necessity itself rests entirely and exclusively on the Principle of Sufficient Reason, because to be necessary, and to result from a given reason, are convertible terms; that the Principle of Sufficient Reason is still nothing but the common form of the Object as such: therefore that it always presupposes the Object and does not, as valid before and independently of it, first introduce it, and cannot make the Object arise in conformity with its own legislation. Thus this starting from the Object and the above-mentioned starting from the Subject have in common, that both presuppose what they pretend to derive: i.e., the necessary correlate of their starting-point."
This last assertion "that the Principle of Sufficient Reason already presupposes the Object, but does not, as valid before and independently of it, first introduce it, and cannot make the Object arise in conformity with its own legislation," seemed to me so far to clash with the proof given by Schopenhauer in § 21 of the "Fourfold Root," as, according to the latter, it is the function of the Subject's understanding which primarily creates the objective world out of the subjective feelings of the sensuous organs by the application of the Principle of Sufficient Reason; so that all that is Object, as such, after all comes into being only in conformity with the Principle of Sufficient Reason, consequently that this principle cannot, as Schopenhauer asserted in his polemic against Fichte, already presuppose the Object. In 1852, therefore, I wrote as follows to Schopenhauer:—
"In your arguments against Fichte, where you say that the Principle of Sufficient Reason already presupposes the Object, and cannot, as valid before and independently of it, first introduce it, the objection occurred to me anew, that in your "Fourfold Root" you had made the Object of perception first come into being through the application of the Principle of Sufficient Reason, and that you yourself, therefore, derive the Object from the Subject, as, for instance, p. 73 of the "Fourfold Root" (2nd edition). How then can you maintain against Fichte that the Object is always pre-supposed by the Subject? I know of no way of solving this difficulty but the following: The Subject only presupposes in the Object what belongs to the thing in itself, what is inscrutable; but it creates itself the representation of the Object, i.e. that by which the thing in itself becomes phenomenon. For instance, when I see a tree, my Subject assumes the thing in itself of that tree; whereas the representation of it conversely presupposes the operation of my Subject, the transition from the effect (in my eye) to its cause."
To this Schopenhauer replied as follows on the 12th of July, 1852:—
"Your answers (to the objection in question) are not the right ones. Here there cannot yet be a question of the thing in itself, and the distinction between representation and object is inadmissible: the world is representation. The matter stands rather as follows—Fichte's derivation of the Non-Ego from the Ego, is quite abstract:—A = A, ergo, I = I, and so forth. Taken in an abstract sense, the Object is at once posited with the Subject. For to be Subject means, to know; and to know means, to have representations. Object and representation are one and the same thing. In the "Fourfold Root," therefore, I have divided all objects or representations into four classes, within which the Principle of Sufficient Reason always reigns, though in each class under a different form; nevertheless, the Principle of Sufficient Reason always presupposes the class itself, and indeed, properly speaking, they coincide.[8] Now, in reality, the existence of the Subject of knowing is not an abstract existence. The Subject does not exist for itself and independently, as if it had dropped from the sky; it appears as the instrument of some individual phenomenon of the Will (animal, human being), whose purposes it is destined to serve, and which thereby now receives a consciousness, on the one hand, of itself, on the other hand, of everything else. The question next arises, as to how or out of what elements the representation of the outer world is brought about within this consciousness. This I have already answered in my "Theory of Colours" and also in my chief work,[9] but most thoroughly and exhaustively of all in the Second Edition of the "Fourfold Root," § 21, where it is shown, that all those elements are of subjective origin; wherefore attention is especially drawn to the great difference between all this and Fichte's humbug. For the whole of my exposition is but the full carrying out of Kant's Transcendental Idealism."[10]
I have thought it advisable to give this passage of his letter, as being relevant to the matter in question. As to the division in chapters and paragraphs, it is the same in this new edition as in the last. By comparing each single paragraph of the second with the same paragraph of the present edition, it will be easy to find out what has been newly added. In conclusion, however, I will still add a short list of the principal passages which are new.