MORAL TALES by Jules Laforgue; translated with an introduction by William Jay Smith; drawings by the author; (New Directions: $17.95, hardcover; $8.95, paperback; illustrated). This is caviar. "Hamlet or the Consequences of Filial Piety," one of the six tales served up, begins the feast. We find the Prince in gray Elsinore in his gray chambers gazing out upon the gray sand, and he brooding, a consequence of "his father's irregular decease," and, yes, that wretched view from the yellowed window "opening upon the soiled gray heavens, the broad sea, and the futility of existence." Hamlet has not been entirely idle, or if you wish, cerebral, for he has recently fashioned two small wax figures (now kept under lock and key) and pierced them through the heart with a vengeful needle. They are of course effigies of the impetuous Gertrude, and the adulterous, fratricidal Claudius. Suddenly the brooding ends: The actors have arrived. Hamlet pumps adrenaline as his eyes fasten on the troupe's bewitching star, and pumps the more as she, sweet Kate, mouths the lines of his own virtuoso "Mouse-trap" script. O love . . . art . . . theater--O joy! Here in "Hamlet" and throughout the tales, Jules Laforgue, the great French symbolist poet and belletrist who died of consumption at 27 in 1887, becomes auteur . The legendary, larger-than-life figures who appear in five of the stories (Hamlet, Lohengrin, Salome, Perseus and Pan) are retrofitted to the measure of his own time--a modern concept and one that paved the way for Ulysses, for example, to reappear in James Joyce's work and answer to the more modest name of Leopold Bloom. Laforgue's influence on modern literature has been extensive as seen not only in Joyce but in the works of Mallarme, Apollinaire, Strindberg, Proust, Pound and Eliot, to name but a few. So wither Hamlet? Off to Paris! Let Denmark rot. Off to set the world of theater ablaze with that glowing persona of his . . . his talent . . . his Kate. But, alas! he detours through the graveyard where the intemperate Laertes lurks, thus Fate (so vulgar at times) cuts him down; cracks that noble heart so full of love . . . at long last, so carefree! Order is restored at Elsinore. Of the six, "Hamlet" is the most engaging, but none is so utterly exquisite as "The Miracle of the Roses" with its consumptive heroine--nor as autobiographical.