The author has dwelt, especially in the theoretical part, upon general questions which are side-issues in respect to the theme that he has treated. But this will not seem a digression to those who remember that, strictly speaking, there are no particular philosophical sciences, standing by themselves. Philosophy is unity, and when we treat of Æsthetic or of Logic or of Ethics, we treat always of the whole of philosophy, although illustrating for didactic purposes only one side of that inseparable unity. In like manner, owing to this intimate connexion of all the parts of philosophy, the uncertainty and misunderstanding as to the æsthetic activity, the representative and productive imagination, this firstborn of the spiritual activities, mainstay of the others, generates everywhere else misunderstandings, uncertainties and errors: in Psychology as in Logic, in History as in the Philosophy of Practice. If language is the first spiritual manifestation, and if the æsthetic form is language itself, taken in all its true scientific extension, it is hopeless to try to understand clearly the later and more complicated phases of the life of the spirit, when their first and simplest moment is ill known, mutilated and disfigured. From the explanation of the æsthetic activity is also to be expected the correction of several concepts and the solution of certain philosophic problems which generally seem to be almost desperate. Such is precisely the spirit animating the present work. And if the present attempt and the historical illustrations which accompany it may be of use in winning friends to these studies, by levelling obstacles and indicating paths to be followed; if this happen, especially here in Italy, whose æsthetic traditions (as has been demonstrated in its place) are very noble, the author will consider that he has gained his end, and one of his keenest desires will have been satisfied.