On November the 14th 1974, Jack Cornaz died in Lausanne, the town where he was born in 1886. This study traces the unusual career of this architect – a singular figure in the field of Swiss-French architecture of the twentieth century – whose name, from the 1920s, is associated with a wide range of neo-classical buildings on the shores of Lake Geneva, and analyses its context. Labelled both marginal and a dissident – depending on the standpoint of the critic – Cornaz's production is presented for the first time, through minute exploration of his unpublished archives, extensive information gathered in the course of interviews with numerous protagonists, both near and far, of the "cornazian scene", and comprehensive lateral research. Diversified in terms of quantity, and yet so uniform in terms of typology and program, his production appears consistent enough to express in itself the themes and motives which permit an understanding of both the variety of its expressions and in the unity of its intentions. The analysis of some of its nodal points – types of clients, production under influences, relevance of the old, problematic relationship to the tradition – provides an opportunity to grapple with broader architectural issues, some including ontological dimension : notion of imitation, bound to a style, relations between the architect and his patronage, autobiographical nature of his relation to the object, properties of the settlement... Though considered as a passéiste architect, Cornaz – at least at the start of his career – appreciated a form of modernity, understood as a progressive development of classical and regional types into a new language, which did not reject or betray the heritage of the past. In this respect, his work may be considered as representative of one of those traditionalist tendencies taken into account by the history of architecture over the last two decades. Based on the analytical cataloguing of the architect's archives deposited in the ACM (Archives of Modern Construction, Lausanne), the method applied in this study is a cross-disciplinary approach combining historical research with the principles of anthropological investigation. It is also based upon the interlocking of two propositions : it is a historical inquiry analysing sources as well as an epistemological reflection about cognitive procedures at work in the material in question. Adept at disciplinary nomadism and in mimetic fit with her object, the author applies a "patchwork" method. She is convinced that the effect of contiguity and accumulation is meaningful in itself, and that the interest of this matching of quotations, which leads to admittance for the need of the gaps and interplay of the elements, resides in its unsteadiness, like in a mosaic. The book consists of two closely connected volets. Chapters are thematic in the first one, these theoretical essays are completed with monographs of twenty of J. Cornaz's constructions and catalogue entries for his works.