Most of us are content to leave our valentine expressions safely in the hands of Hallmark. In this electronic age of the spoken work, love's verbosity generally takes place on the telephone. But you can't take that out of your pocket to read and swoon over later. Love Letters, an anthology of 135 wonderful testimonies to Cupid, chosen by beauteous biographer Antonia Fraser (who ought to know a good love letter when she sees one) should inspire valentine-givers to more literary heights. They are letters passions, ecstassies, beginnings, ending and thirteen other categories. Writers include Keats, Napoleon, Chopin, Proust, Sarah Bernhardt, Zelda Fitzgerald and Henry V111 to Anne Boleyn (before she lost her head over that affair). To satisfy reader curiosity about what happens next, Fraser includes biographical detail on the lasting attachments or passing infatuations of the correspondents. All outpourings are of the heart-on-the-sleeve variety and may have you leaping madly for pen and ink to commit similar prose to paper. Beware you don't make it too similar, especially if your beloved is well read. And certainly do not follow the included brief missive of the Prime De Joinville, who, in 1840, sent the notorious French actress Rachel these few choice words, "Where? - When? - How Much?"

Love Letters, by Antonia Fraser. Alfred A. Knopf, $8.95.