been said, why the deductive philosophy has never yet succeeded in reaching the majority of the educated, but has had to be contented with a limited public, and why it has been just as little successful in bridging over the vast gulf which separates it from the reality to be explained. Those philosophies, on the contrary, where the inductive method has been adopted, and all the natural sciences in the widest sense of the term, have undoubtedly obtained precious results of a secondary kind and gained ground for the future, but still are very far indeed from having reached ultimate principles and the true unity of science. Thus a chasm yawns between the methods; induction cannot attain to first principles and to system, nor can pure speculation arrive at explanation of the actual or communicate its wisdom. It may be concluded from this that the whole truth cannot be comprehended from one side alone, but that the matter must be approached simultaneously from both sides, and a survey made from opposite stations in order to find out the salient points, where a bridge can be thrown across. For the case is not an entirely hopeless one. Thoughts crystallise both from above and from below, as the mass of melted sulphur coalesces when the most prominent needles interlace, but not before. We have arrived at a point in the history of science where the pioneers meet, like two miners who, in their subterranean galleries, hear each other's knocking through the partywalls. For inductive science has in recent times made such vast progress in all branches of inorganic and organic nature, and even in the region of mind, that attempts of the kind indicated find a very different ground on which to work than, c.g., those of an Aristotle, Paracelsus, Bacon, and Leibniz. On the other hand, however, the period embracing the close of the last and beginning of the present century, brilliant beyond all former periods, has enriched the speculative mind in so many ways, that both parties once more face each other as equals. But at the same time the world has become more aware of a direct antagonism of method which before was less apparent, and hence it has come to pass that each investigator is wont to declare himself for one of the two tendencies much more definitely than was formerly the case. The present time needs a spokesman who has comprehended both sides with equal love and devotion, who is capable, if not of mystical production, yet of reproduction, and at the same time has made a survey of exact science and appreciates the strictness of the exact inductive method. He should clearly recognise, too, the nature of the problem before him, viz., to combine the speculative (mystically gained) principles with the highest results hitherto attained of inductive science according to inductive method, in order to bridge over the gulf between the two, and to elevate what have hitherto been merely subjective convictions to the rank of objective truths. It was in reference to this great and seasonable problem that I chose the motto, "Speculative results according to inductive scientific method!" Not that I thought myself to possess a mind sufficiently comprehensive for the solution of this problem, or at all believed that I had offered in the present work a satisfactory solution, that is far from me. If I merit any praise, it is for having distinctly declared a problem, already recognised and attacked in different ways, to be the philosophic problem of a time suffering conspicuously from speculative exhaustion, for resolving to contribute my mite towards its solution, and so giving to others a possibly needed stimulus; but above all, because I have taken up the matter on a side hitherto neglected, but rich in promise beyond all others. At the same time 1 The astonishingly favourable reception, which the previous editions of this work have met with, seems to me to be essentially due to a recognition of the seasonableness of my efforts. my design imposes upon me the duty of submitting myself to the judgment of both tribunals, the scientific as well as the philosophical.1 Gladly do I do this, however; for I hold all speculation to be baseless, which contradicts the clear results of empirical investigation, and conversely hold all conceptions and interpretations of empirical facts to be erroneous, which contradict the strict results of a purely logical speculation. I may perhaps be allowed to say also a few words upon the mode of exposition. My first rule has been general intelligibility and brevity. The reader will accordingly find no citations except such as could be worked into the text; all polemic has been avoided as far as possible, unless it was indispensable for the elucidation of a conception. My trust is greater in the convincing power of what positive truth there may be contained in my work than in negative criticism, however incisive. Further, instead of dwelling upon the errors and weaknesses of great men, which receive 1 The criticisms and replies, whether philosophical or scientific, which have come under my notice, have not succeeded in shaking my opinions on any material point, but have rather strengthened them in several instances. In the Addenda to the earlier editions I sought as much as possible to avoid polemics, and allowed myself for the first time in the Appendix to the seventh edition somewhat greater liberty in this respect. I have permitted my self more freedom in respect to controversy in some minor writings. A fuller treatment of strictly scientific questions will be found in "Truth and Error in Darwinism,' and "Contributions to a Philosophy of Nature" (Section C. of "Gesammelte Studien und Aufsätze gemeinverständlichen Inhalts"), as well as in the Appendix to the present volume, "On the Physiology of the Nerve-Centres." My place in the historical development of philosophy is indicated in 64 Elucidations of the Metaphysic of the Unconscious." The following writings give a clue to my position in respect to the problems of the theory of knowledge and metho dology :-"Kritische Grundlegung des transcendentalen Realismus," 2d ed.; "J. H. v. Kirchmann's erkenntnisstheoretischer Realismus" and "Ueber die dialektische Methode." On the religious questions of the present day I have expressed my opinions in the tractate "Die Selbstzersetzung des Christenthums und die Religion der Zukunft," 2d ed., and a few excursuses in the field of Esthetics are to be found in "Aesthethische Studien " (Section B. of the "Gesammelte Studien und Aufsätze " sentence in being forgotten in course of time, I have preferred to render prominent their grandest ideas, where they presagingly foreshadow in vague outline what only the future can establish in complete detail. Further, the opportunity for interesting side-remarks, for more thorough but prolix proofs, detailed deductions, &c., has often been left unused, so as to avoid a lengthened treatment, which would be serviceable to but a few readers. Accordingly, in the majority of instances, with the exception of those which deal with fundamentals, the chapters are almost aphoristic, because I believe that most readers will prefer a short exposition affording stimulus to self-reflection to an exhaustive treatment of the subject. In the handling of the topics the reader's convenience has also been considered as far as possible, in that each chapter forms a little treatise by itself on a limited subject (a few only making an exception to this which belong inseparably together, as, e.g., Chap. C. vi. and vii.) The chapters of the first two sections together and severally prove the existence of the Unconscious; their concord and demonstrative force is a source of mutual support, and they sustain each other reciprocally like a pile of arms; thus the later support the earlier. I therefore beg the reader kindly to reserve his judgment, at least until he has finished Section A. Should, however, the proof of this or that chapter appear to be faulty, the inferences of the others are not necessarily thereby condemned, just as one or many of the weapons may be taken from a pyramid of piled arms without its collapsing. Lastly, I crave indulgence so far as the several physiological and zoological facts employed as examples are concerned, in respect to which a layman may easily make a slip, without, however, prejudicing the main argument. (c) Predecessors in respect of the Conception of the What a time elapsed before in the history of Philosophy the antithesis of Spirit and Nature, Thought and Being, Subject and Object, emerged into clear consciousness, an antithesis which now governs all our thinking! For the primitive man as natural existence felt his body and soul to be one, he instinctively anticipated this identity, and his understanding must have reached a high degree of consciousness, before he could so far free. himself from this instinct as to perceive the full force of the contrast. Nowhere in all Greek philosophy do we find this opposition clearly expressed, still less its significance recognised, but least of all in the classical period. If this holds good of the opposition of the Real and the Ideal, ought we to be surprised that the contrast of the Unconscious and the Conscious should still less occur to the primitive understanding, and therefore should arise much later in the history of Philosophy; nay, that at this very day most educated people hold it to be absurd to speak of unconscious thinking? For the Unconscious is so much terra incognita to the natural consciousness, that it regards the identity of having an idea and being conscious of a thing as quite self-evident and indubitable. This naïve point of view was taken by Descartes (Prin. Phil., i. 9), and still more decidedly by Locke (Essay on the Human Understanding, book ii. chap. 1, sec. 9): "To ask at what time a man has any ideas is to ask when he begins to perceive, having Ideas and Perception being the same thing;" or sec. 19: "For it is altogether as intelligible to say that a body is extended without parts, as that anything thinks without being conscious of it. They who talk thus may, with as much reason, if it be necessary to their hypothesis, say that a man. is always hungry, but that he does not always feel it; whereas hunger consists in that very sensation, as think |