Francesco de Sanctis was not a philosopher in the strict meaning of the word; yet, among all the European critics of the nineteenth century, he is the only one from whose works it is possible to derive a consistent line of æsthetical thought. His education had been partly philosophical, of old Italian and modern German philosophy; and partly grammatical and rhetorical, in those literary doctrines of the old school which embodied a secular experience, and in comparison with which the modern _science_ of literature is ineffably shallow and puerile. It was through a philosophical elaboration of those doctrines, and through a criticism of the intellectualistic æsthetics of Hegel and his followers, for whom art was the sensuous clothing of the concept, that De Sanctis, guided by an unerring taste and by a unique power for discerning the essential and vital element in poetry, came to his conception of form as not an _a priori,_ a thing by itself and different from the content, but something that is generated by the content itself when active in the mind of the artist. This is the principle which he had constantly in mind in approaching the concrete works of poetry, and which enabled him to analyze and reproduce the terms of the spiritual experiences of which they are an expression. Thus his _Essays_ and his _History of Italian Literature,_ though in a sense the purest and most genuine kind of literary criticism, are at the same time a complete spiritual history of a people, as it reveals itself in its literary manifestations, such as no other country possesses. The immediate influence of his work was not as great as it ought to have been: the generation of philologists who immediately followed him was unable to see in him more than a brilliant exponent of what was then contemptuously called æsthetic criticism, and could never forgive him for his apparent lack of method, due to the circumstances of his life as an exile and a politician. It was only unwittingly, and through the intermediary of a German disciple of De Sanctis, Gaspary, who wrote a standard handbook of Italian literature, that they came to accept the greatest part of his interpretations, and followed the main directions of his thought in their own researches.