Its approach moves always from the particular to the general, following through the steps of the abstraction process until the abstract concept emerges naturally.Beginning with a survey of set theory and its role in mathematics, the text proceeds to definitions and examples of categories and explains the use of arrows in place of set-membership. The introduction to topos structure covers topos logic, algebra of subobjects, and intuitionism and its logic, advancing to the concept of functors, set concepts and validity, and elementary truth. Explorations of categorial set theory, local truth, and adjointness and quantifiers conclude with a study of logical geometry.

    The author sees this expression as an emphasis on the significance of the individual living in community and on the person in the process of performing an action. The author states in his preface that he has tried to face the major issues concerning life, nature, and the existence of Man directly as they present themselves to Man in his struggles to survive while maintaining the dignity of a human being, but who is torn apart between his all too limited condition and his highest aspirations to set himself free.The author hopes that his book "contributes to this disentangling of the conflicting issues facing Man, which are crucial for Man s own clarification of his existence and direction of his conduct."The author s analysis of the human being is a dynamic counter to the materialistic and positivistic tendencies in various schools of modern philosophy. Ever since Descartes, the knowledge of Man and his world has been identified through cognition. This book is a reversal of the post-Cartesian attitude toward Man in that it characterises him as the person in action.Audience: The Acting Person will be of great interest to philosophers, anthropologists, and scholars specializing in phenomenology. It will also be of deep concern to theologians, priests, seminarians, and members of religious orders who wish to gain an insight into Pope John Paul II s philosophy of life. "