The reader who desires a complete statement of the general or collateral doctrines or a more particular exposition of the other parts of philosophy (_e.g._ the lyrical nature of art) is now referred to the volumes on _Logic_ and the _Philosophy of Practice,_ which together with the present work compose the _Philosophy of the Spirit_ which in the author's opinion exhausts the entire field of Philosophy. The three volumes were not conceived and written simultaneously; if they had been, some details would have been differently arranged. When I wrote the first I had no idea of giving it, as I have now done, two such companions; and I therefore designed it to be, as I say, complete in itself. In the second place, the present state of the study of Æsthetic made it desirable to append to the theoretical exposition a somewhat full history of the science, whereas for the other parts of Philosophy I was able to restrict myself to brief historical notes merely designed to show how, from my point of view, such a history would best be composed. Lastly, there are many things which now, after a systematic exposition of the various philosophical sciences, I see in closer connexions and in a clearer, or at least a different, light; a certain hesitation and even some doctrinal errors visible here and there in the _Æsthetic,_ especially where subjects foreign to Æsthetic itself are being treated, would now no longer be justified. For all these reasons the three volumes, in spite of their substantial unity of spirit and of aim, have each its own physiognomy, and show marks of the different periods of life at which they were written, so as to group themselves, and to demand interpretation, as a progressive series according to their dates of publication. With what may be called the minor problems of Æsthetic, and the objections which have been or might be brought against my theory, I have dealt and am continuing to deal in special essays, of which I shall shortly publish a first collection which will form a kind of explanatory and polemical appendix to the present volume. _November_ 1907. In revising this book once more for a fourth edition, I take the opportunity of announcing that the supplementary volume of essays promised above was published in 1910 under the title _Problems of Æsthetic and Contributions to the History of Æsthetic in Italy._ B. C. _May_ 1911. THEORY OF ÆSTHETIC I INTUITION AND EXPRESSION [Sidenote: _Intuitive knowledge._] Knowledge has two forms: it is either _intuitive_ knowledge or _logical_ knowledge; knowledge obtained through the _imagination_ or knowledge obtained through the _intellect_; knowledge of the _individual_ or knowledge of the _universal_; of _individual things_ or of the _relations_ between them: it is, in fact, productive either of _images_ or of _concepts._