What is the origin of current ideas about risk? Why the obsession with that concept? What is the relationship between conceptions of risk and the formal discipline of finance? In view of human limitations, how useful are recent developments? These questions are the main object of exploration of this book. Maintaining a commitment of fidelity, the author presents the original ideas that have prevailed as distinctive of this field of study. The result is a work that provides conceptual tools to its readers to approach, in a critical way, the problems posed by the current world and to investigate, on their own terms, the foundations of the discipline. The form of exposition, a mixture of somewhat informal style with formal content, seeks to reach a wider university community than the one targeted by books with a focus on instruction.