After a year and a half of sellout performances in New York, Lena Horne brought her Broadway show, "Lena Horne: the Lady and Her Music," to Wolf Trap's Meadow Center for a two-night stand, which may be the underbooking of the year. The way she picks up an audience, cajoles, it, lectures it, caresses it and generally knocks it senseless with enthusiasm, the indestructible lady could run here until the first snows of winter. In a locale accustomed to conflagrations, she carries on merely like a house afire.

No nostalgia outing, this. Granted, Horne pays wry tribute to her sultry screen image of the 1940s, when all that Hollywood could think to do with her was to have her purr and pout up against a pillar in a series of forgettable musicals. And there is a fair share of standards in the 2 1/2-hour repertoire--"Stormy Weather," "The Lady Is a Tramp," "Watch What Happens," "Can't Help Loving Dat Man." But even when she's singing the old standards, she's singing them very much for today.

At 65--somebody surely made a mistake on the birth certificate--she has never been so sure of her identity: loose as a limbo dancer, down home as a pot of greens and sexier than most women half her age. Despite a sound system with all the finesse of Grand Central Station's, her voice goes from a tremulous hush to earthy passion with the greatest of ease. The consonants are still lettuce-crisp, but there's a new gutsiness as well.

Take "Bewitched, Bothered and Bewildered." The Larry Hart lyrics are the epitome of sophistication and time was when Horne would have gone for the supper-club class. No longer. Indicatively, she introduces the number as being about "a broad with money" and a "superstud," then proceeds to tear into it with a kind of street savvy that makes the song brand-new--not quite raunchy, but getting there.

In the course of the evening she also talks about her roots, her ups and downs in show business and her new-found philosophy of loving. "It ain't about singing in the shower," she said at one point, passing on the key to her success. "It's about hard work, sweating, showing up on time . . . and daring to make a damn fool of yourself."

Call her a pro. Simple as that.