IT'S A BALLET REHEARSAL like most others -- there are three dancers, a man and two women. A tape playing a Chopin piano score. And a rehearsal mistress, watching intently, taking notes and frequently interrupting the dancing to correct the performers.

But the man in the wheelchair at the back of the room is the one really in charge. Reclining slightly, draped in a blanket, Eric Hampton is motionless, silent. His eyes don't leave the dancers. They are rehearsing his work, "Nocturne 1," preparing for this weekend, and he wants to make sure they get it right.

"Eric, do we need to do that again?" asks Harriet Moncure Williams, the rehearsal mistress. Hampton blinks. The breathless dancers -- Peter Stark, Emily Beeny and Joie Meffert -- begin again.

Hampton has Lou Gehrig's disease, a paralyzing illness that has robbed him of nearly all movement. He can move his head slightly from side to side, smile if amused (which during this rehearsal he frequently is) and blink his eyes. It is by eye blinks that he speaks. One blink means yes, a fixed stare means no.

To help Hampton say more, one of the several friends seated nearby holds up a clear plastic square with letters printed on it. Hampton moves his eyes from letter to letter, spelling out one word, then perhaps another, with excruciating slowness. There's often confusion about which part of the board he's focusing on, and what letter he's choosing. But those in the studio on this day at the Maryland Youth Ballet in Bethesda have a long history with Hampton, who before the disease's swift progression was a revered ballet teacher and gifted choreographer with his own company, Eric Hampton Dance. So some measure of mind-reading seems to be going on.

N-O-E-X-T, he spells. "No extra?" asks Carrie Paape, who is holding the letter board. He stares at her. "No extension?" asks Williams. Hampton blinks. "Don't do the extra battement," Williams translates for Meffert. "Just put your foot down."

"Ooh, that's hard," whispers Alison Crosby, a prominent local dancer who performed in the last production of "Nocturne 1," back in 1986. "He just wants her to stick it."

"That's so Eric," whispers costume designer Judy Hansen, with a knowing laugh.

Though the afternoon stops and starts a hundred times, the final run-through of the short ballet is an engrossing wordless drama, perfect in its evocation of the confusion and temptation of love. But it is not only the dancers and the assembled onlookers who are moved by the process. Asked what it means to him to be able to venture out of his nursing home to rehearse these dancers in his ballet, Hampton spells out one word: "L-I-F-E."

ERIC HAMPTON DANCE and KAREN & ALVIN -- Saturday at 8 p.m., Sunday at 7 p.m. at the Jewish Community Center of Greater Washington, 6125 Montrose Rd., Rockville. $12-$15. Call 301/230- 3775.