W.B. Yeats & George Yeats: The Letters Edited by Ann Saddlemyer (Oxford University Press, 599 pp., $49.95) Words Alone: Yeats & his Inheritances By R.F. Foster (Oxford University Press, 236 pp., $29.95) IT WAS CERTAINLY an odd marriage. The groom, already a well-known Irish poet, was fifty-two, the bride twenty-four. The groom had proposed to two other women immediately before settling for the bride, a well-bred young Englishwoman whom he had known for several years and with whom he shared occult interests.