In a sense it may be said that the key to every system of philosophy is to be found in the either implicit or explicit solution given to certain logical problems and that only by understanding the logic of a philosopher can we be sure to give its true meaning and value to his thought. The reverse is, as a general rule, also true: any solution of a particular problem, any particular elaboration of the concept, when fully understood, will lead us back to the philosopher's logic, to his concept of the concept. The main points of Croce's logic could easily be deduced from his æsthetics; but an untrained mind might unwittingly transpose the whole æsthetic theory on a purely psychological plane, and involve it again in the errors and contradictions of which it aims at being a conclusive refutation. A study of Croce's logic will render such a shifting of the perspective impossible. It will show that a discussion of Croce's æsthetics has no meaning except on the logical plane on which Croce has put it, and that therefore any serious objection to it ought necessarily to imply either a revision of the logical premises, or a demonstration that the actual logical processes are not rigorously in accord with these premises. What is here said of Croce's æsthetics is valid also for Croce's economics or ethics, and the reason is obvious. Croce's _Logica_ is not a manual of logic, in a scholastic and formalistic sense: it is the exposition of his conception of the logical activity, and therefore the philosophy of his philosophy.