What is defense? To this day, the negative aspect of its functions dominates: the defender restricts themselves, conceals essential and personal aspects, and simultaneously distances themselves from their own self. In doing so, we overlook the constructive function of defense, which enables the subject not only to endure the numerous restrictions and demands during their socialization but also to utilize them for the development of their personality and the refinement of their aesthetic and cultural life. This book provides a detailed account of the history of defense concepts and examines the central role of defense processes in personality development.