Who besides the authors' friends would guess that the letters of F. O. Matthiessen and Russell Cheney (affectionately, the Devil and Rat) record a love story, touching, ingenuous, often consuming and ennobling? From the first encounter in 1924, when Matthiessen was 22 and Cheney 43, to Cheney's death in 1945 (Matthiessen died by his own hand five years later), the scholar and the painter periodically shared lives, thoughts, feelings, and sexual pleasure. ""I'm sure I repeat myself,"" Matthiessen wrote near the beginning, ""but what difference does it make when you have given your whole self to a feller?"" That confessional openness resembled the Romantic ideal of perfect union; but since this union bound two men, the letters become an affecting record of homosexual love, including the early guilt, the lapses of sympathy, and the remaking of life. The letters include mare than talk of love, of course. As the years pass, and Matthiessen remains at Harvard while Cheney resides much of the time in the West, with summers and holidays spent together, the two exchange commonplaces, and news of work: Cheney searches for a confident, distinctive style, gaining modest recognition; Matthiessen develops his ""New Standards of American Criticism,"" writes and reviews countless works, and succumbs to suicidal depression. Thus, despite the unforgivable quantity of insignificant matter here, the authors' friend Louis Hyde has edited, with connective commentary, an intriguing document in American cultural history.