Published in 1946, this volume does not purpose to be a treatise on logic. The author's contributions to the substance of logical doctrine have been made in his other works. What he has attempted in the studies that form this volume is an exploration of the periphery of logic, the relation of logic to the rest of the universe, the philosophical presuppositions which give logic its meaning and the applications which give it importance. It is his belief that formal logic is the heart of philosophy, since the subject matter of logic is the formal aspect of all being. From this standpoint he explores the relation of logic to such fields of study as natural science, ethics, history and general philosophy.