Abstract
This paper is devoted to an analysis of the intellectual itinerary of Louis de Broglie, from the discovery of wave mechanics, until today. Essential attention is paid to the fact that this itinerary is far from being linear, since after a first attempt to develop his own views on wave mechanics through the theory of singular waves, Louis de Broglie abandoned it for twenty five years, under the influence of the Copenhagen School (even embracing the conceptions of the latter), until the beginning of the fifties, when he definitively came back to his primary theory. This evolution of the Louis de Broglie's views on wave mechanics is told here and explained through an analysis of the evolution of all of quantum mechanics and, more generally, the dominating conceptions of theoretical physics in our century.This paper is written in a quite personal form, which is not exactly one to which the readers of scientific journals are accustomed, because it reproduces, in fact, the preface of a book (to be published) of Louis de Broglie, which is precisely devoted to the fundamental problems of quantum mechanics and closely linked to the second turnabout of the author