This volume consists of the first of the John Dewey Lectures delivered under the auspices of Columbia University’s Philosophy Department as well as other essays by the author. Intended to clarify the meaning of the philosophical doctrines propounded by W. V. Quine in Word and Objects, the essays included herein are intimately related and concern themselves with three philosophical preoccupations: the nature of meaning, the meaning of existence and the nature of natural knowledge.