We shall soon see from which source Croce derived his interest in economic problems and in the history of the practical activities of man. Of the permanence of those moral preoccupations which had been his constant companions since his adolescence, we find the traces in his autobiographical notes. In De Sanctis, whose _History of Italian Literature_ is as much a moral as an æsthetic history of the Italian people, he had the model of "a sound and simple morality, austere without exaggerations, and high without fanaticisms."[10] But the same difficulties which prevented him from fully understanding De Sanctis' æsthetic principles, and from using them as a vivifying element in his literary work, made him also for a long time accept an inferior moral conception, that of Herbart's realism, "in which the moral ideal was energetically asserted, but as a thing of another world, as having man under itself as brute matter, on which its stamp, more or less marked, might or might not be impressed." That is, he saw the moral ideal in relation to the actual life of man, in a position similar to that which concepts and ideals had for him in relation to reality as a whole: his moral abstractism and rigorism was the counterpart of his logic. "But that rigorism and abstractism was the way that I had necessarily to follow in order to understand the moral concreteness, and to lift it to the plane of a philosophical theory." "And that rigorism, which was at the same time a love for sharp distinctions, while it saved me from associationism and positivism and evolutionism, put me on my guard against, and hindered me from falling into the errors of that now naturalistic, now mystic, Hegelianism, which through a hasty and often mythological dialectic, obliterated or weakened the distinctions which are the life of the dialectic process."[11] What Croce lacked, in ethics as well as in æsthetics, was a new logic or theory of knowledge, which would allow him to grasp the concept or the ideal, that is the universal, in the concrete spiritual activity, that is in the particular and individual. Meanwhile, his own dealing with abstract concepts, with purely formal universals, was to be, in relation to the further developments of his logic, what his early literary work, of a purely erudite character, had been in relation to his meditations on art and history: that personal experience, of difficulties and errors, without which no truth can ever be reached.