Furthermore, concrete truths relating to historical events have often been expressed beneath the false and presumptuous cloak of a philosophy of history; canons and empirical advice have been formulated by no means superfluous to students and critics. It does not seem possible to deny this utility to the most recent of philosophies of history, to so-called historical materialism, which has thrown a very vivid light upon many sides of social life, formerly neglected or ill understood. [Sidenote] _Aesthetic invasions into Logic._ The principle of authority, of the _ipse dixit_, is an invasion of historicity into the domains of science and philosophy which has raged in the schools. This substitutes for introspection and philosophical analyses, this or that evidence, document, or authoritative statement, with which history certainly cannot dispense. But Logic, the science of thought and of intellectual knowledge, has suffered the most grave and destructive disturbances and errors of all, through the imperfect understanding of the aesthetic fact. How, indeed, could it be otherwise, if logical activity come after and contain in itself aesthetic activity? An inexact Aesthetic must of necessity drag after it an inexact Logic. Whoever opens logical treatises, from the _Organum_ of Aristotle to the moderns, must admit that they all contain a haphazard mixture of verbal facts and facts of thought, of grammatical forms and of conceptual forms, of Aesthetic and of Logic. Not that attempts have been wanting to escape from verbal expression and to seize thought in its effective nature. Aristotelian logic itself did not become mere syllogistic and verbalism, without some stumbling and oscillation. The especially logical problem was often touched upon in the Middle Ages, by the nominalists, realists, and conceptualists, in their disputes. With Galileo and with Bacon, the natural sciences gave an honourable place to induction. Vico combated formalist and mathematical logic in favour of inventive methods. Kant called attention to _a priori_ syntheses. The absolute idealists despised the Aristotelian logic. The followers of Herbart, bound to Aristotle, on the other hand, set in relief those judgments which they called narrative, which are of a character altogether different from other logical judgments. Finally, the linguists insisted upon the irrationality of the word, in relation to the concept. But a conscious, sure, and radical movement of reform can find no base or starting-point, save in the science of Aesthetic. [Sidenote] _Logic in its essence._