Weiss does for Mozart pretty much what he did for Rodin in Naked Came I--an historical novel which disclaims being either biography or a romance and which is dominated by two considerations: ""a respect for the historical fact and a need to supply the missing details in terms of human behavior."" In the case of the former, he does indeed maintain a respectful solemnity of responsible recording. As for the latter--Mozart emerges as a mannikin, first manipulated by his father who believed in his gift (and did not promote him for gain--another interpretation), later at the mercy of capricious patrons and a possibly faithless wife. Mozart, however, remained a devoted son and husband in spite of the temptation of his Susannah, Ann Storace, and others who made themselves available. Mr. Weiss describes the circumstances of composing without any demonstrable understanding of the music beyond the most capricious judgments, (""Your music is all heart"" says one admirer). . . . Ein Grosses Nacht Musik for a popular readership, tone deaf to style.