The author reports on situations experienced by investors which clearly break the rules and norms of accepted rationality, for example when a fall in the price of an asset is accompanied, contrary to the classical hypotheses, by a fall in demand. He outlines a general theory for the fields of choice and the marginal rates of substitution within the framework of a specific referential of the economic subject, of a psychological nature and structured by time-values, and the framework of a limited rationality. In this important and timely book, Blanqué made a powerful claim for positive investment in order to avoid fanciful illusions. He assigned it the task of understanding what is happening in today’s world. Blanqué argued that the investment world contains many elements of a fairy tale and showed that a mere confrontation with reality leaves its mark on the impressive procession of theoretical, sacred cows, of established beliefs and truths. As does the confrontation with crises.