Louis Vierne, one of the most important figures in the rich French organ literature of the late nineteenth and early twentieth centuries, made a substantial contribution in the cultivation and the promulgation of an organ playing tradition which was initiated by Belgian organist Jaak Nikolaas Lemmens. Vierne's aesthetics concerning organ and organ playing were most explicitly given in a treatise which he began during the First World War but never finished in his lifetime and remained unknown to the public until fifty years after his death. This important document was published by Les Amis de l'Orgue in 1987 as a special issue of their periodical L'Orgue together with an introductory article and editorial remarks by the Belgian musicologist Dr. Brigitte de Leersnyder. With an English translation of the aforementioned document, a lengthy biography dealing mainly with Vierne's organ profession, and a survey of the organ methods in Lemmens' tradition, the present study tries to demonstrate Vierne's role in that tradition and aims at providing organists a tool for an authentic interpretation in their performance of Vierne's organ works.