problems which are to be found mingled with the metaphysic of every true philosopher. And although there is no longer a field left over to these scholars who merely faithfully echo the master, like adepts of a religion, there is yet a wide field always open to the other type of scholar, men who pay serious attention and assimilate what is of use to them in the thought of others, but then proceed to state and to solve new problems of their own. Finally, the life of philosophy as conceived and portrayed in this _Logic,_ resembles the life of poetry in this: that it does not become effective save in passing from _different_ to _different,_ from one original thinker to another, as poetry passes from poet to poet, and imitators and schools of poetry, although they certainly belong to the world, yet do not belong to the world of poetry. B. C. _September_ 1916. CONTENTS FIRST PART THE PURE CONCEPT, THE INDIVIDUAL JUDGMENT AND THE _A PRIORI_ LOGICAL SYNTHESIS FIRST SECTION THE PURE CONCEPT AND THE PSEUDOCONCEPTS I AFFIRMATION OF THE CONCEPT Thought and sensation--Thought and language--Intuition and language as presuppositions--Scepsis as to the concept--Its three forms--Æstheticism--Mysticism--Empiricism--_Redactio ad absurdum_ of the three forms--Affirmation of the concept. II THE CONCEPT AND THE PSEUDOCONCEPTS Concept and conceptual fictions--The pure concept as ultra- and omnirepresentative--Conceptual fictions as representative without universality, or universals void of representations--Criticism of the doctrine which considers them to be erroneous concepts, or imperfect concepts preparatory to perfect concepts--Posteriority of fictional concepts to true and proper concepts--Proper character of conceptual fictions--The practical end and mnemonic utility--Persistence of conceptual fictions side by side with concepts--Pure concepts and pseudoconcepts. III THE CHARACTERISTICS AND THE CHARACTER OF THE CONCEPT Expressivity--Universality--Concreteness--The concrete-universal and the formation of the pseudoconcepts--Empirical and abstract pseudoconcepts--The other characteristics of the pure concept--The origin of multiplicity and the unity of the characteristics of the concept--Objection relating to the unreality of the pure concept and the impossibility of demonstrating it--Prejudice concerning the nature of the demonstration--Prejudice relating to the representability of the concept--Protests of philosophers against this prejudice--Reason of their perpetual reappearance. IV DISPUTES CONCERNING THE NATURE OF THE CONCEPT