Whatever sorrows and ecstasies of the secret soul lie artistic mastery, they were at high tide during much of last night's American Ballet Theatre performances at the Kennedy Center. In particular, "La Sonnambula" and "Raymonda," which came off to such drab effect opening night, pulsed to incandescent life this time around. The primary, though by no means sole, reasons were the inspired interpretations of Mikhail Baryshnikov, as the doomed Poet in "Sonnambula," and Natalia Makarova, returning to Washington after a lengthy absence, in "Raymonda."

Neither triumph had much to do with "virtuosity," in its usual connotations.

In Baryshnikov's case, the whole weird drama was implicit in the smallest drama was implicit in the smallest details of his portrayal; you could feel what was coming with his disturbingly haunted entrance. Chrisa Keramidas' Sleepwalker looked to be still in an embryonic stage, but her gaunt beauty and filmy legato make her a natural for the role.

In "Raymonda," Makarova sustained a seductive grandeur despite the emotional detachment of her partner, Kevin McKenzie. Also seen was ABT's new production of Kenneth McMillan's "Concerto," rather silky looking for such a machine-tooled ballet. Cynthia Gregory, Kristine Elliott and Cheryl Yeager profited the most from its chromium highlights.