''Rockaby,'' at the newly named Samuel Beckett Theatre on West 42nd Street, is a case of magnifying the minimal with the lens of artistry. By the depth of their focus, Billie Whitelaw and director Alan Schneider reach for the inherent humanity below the surface of Beckett's bleak landscape of mortality.
Britain's Miss Whitelaw serves the triple bill in a double capacity. The opening segment, ''Enough,'' consists of a dramatic reading of a Beckett short story. Casually costumed (by Carla Kramer) in skirt and blouse, the actress balances involvement and detachment as the first-person narrator of a strange reminiscence about a bizarre relationship. The relationship ended when the storyteller committed a ''disgraceful act,'' the nature of which is not disclosed. Beckett relieves some of the story's prevailing starkness and grotesquerie with lyrical passages about flowers and spring, and even with touches of humor.
''Footfalls,'' the second piece of the evening, concerns an aging daughter who shuffles ceaselessly back and forth outside the door of her (offstage) bedridden mother. In her ''faint tangle of pale gray tatters,'' the stooped, spectral May of this wintry playlet measures the pattern of her life in the multiplied footfalls.
''Will you never have done revolving it all in your poor mind?'' asks the unseen mother (Sybil Lines). In her extraordinary progression vocally and physically, Miss Whitelaw creates the illusion of a diminishing figure. It is almost impossible to detect the exact moment when May disappears, so skillfully is the disappearance achieved and so subtly has designer Rocky Greenberg's lighting harmonized with Miss Whitelaw's performance and Mr. Schneider's direction.
''Rockaby'' treats yet another facet of human sorrow: the bewildering isolation of loneliness. Seated in a stout wooden rocking chair, a Woman (Miss Whitelaw) rocks to and fro to the lilt and rhythm of an offstage commentary (the actress on tape).Except for the occasional, hauntingly delivered word, ''More,'' the seated figure - ''facing other windows, other lonely windows'' - approaches a moment of inevitability that seems to suggest both finality and release.
As in ''Footfalls,'' Miss Whitelaw's masklike makeup supplies sharp visual imagery to compensate for the anti-theatricalism of the austere Beckett brand of playmaking. It is the kind of precise artistry that helps give these plays their compelling power.
An evening like ''Rockaby'' is not for all audience tastes.For those attuned to Beckett's greatness, however, it is an unforgettable experience. With the playwright's triple bill of ''What's Where,'' ''Catastrophe,'' and ''Ohio Impromptu'' playing next door at the Harold Clurman, Theatre Row is offering something of a Beckett mini-festival.