Eros and mortality are the central themes of Roth's frank, unsparing and curious new novella. It's curious not only because of its short form (new for Roth), but because he seems to have assumed the mantle of Saul Bellow, writing pages of essay-like exposition on contemporary social phenomena and advancing the narrative through introspection rather than dialogue. The protagonist is again David Kepesh (of The Breast and The Professor of Desire), who left his wife and son during the sexual revolution vowing to indulge his erotic needs without encumbrance. Kepesh is now an eminent 70-year-old cultural critic and lecturer at a New York college, recalling a devastating, all-consuming affair he had eight years before with voluptuous 24-year-old Consuela Castillo, a graduate student and daughter of a prosperous Cuban migr family. From the beginning, Kepesh is oppressed by the ""unavoidable poignancy"" of their age difference, and he suffers with the jealous knowledge that this liaison will likely be his last; even when locked in the throes of sexual congress, a death's head looms in his imagination. The end of the affair casts him into a long depression. When Consuela contacts him again eight years later, on the New Year's Eve of the millennium, their reunion is doubly ironic in the Roth tradition. Consuela has devastating news about her body, and it's obvious that retribution is at hand for the old libertine. Roth's candor about an elderly man's consciousness that he's ""a dying animal"" (from the Yeats poem) is unsentimental, and his descriptions of the lovers' erotic acts push the envelope in at least one scene involving menstruation. The novella is as brilliantly written, line by line, as any book in Roth's oeuvre, and it's bound to be talked about with gusto. (May 18) Forecast: Roth's audience is faithful, and the erotic explicitness of this book may attract other readers who have not tackled the author's longer novels. But his longtime refusal to do talk shows or give interviews will as usual limit publicity efforts, and it remains to be seen whether such a narrowly focused story will sell with the rapidity of Roth's longer novels.