She made her Met debut in 1977 at the comparatively advanced age of 29 as the Shepherd in Wagner’s Tannhäuser, a part within the compass of a choirboy. Seventeen years later, in 1994, she made front-page news when the company’s hard-headed general director Joseph Volpe fired her for “unprofessional actions” (read: driving colleagues crazy). While her reign lasted, there simply was no reconciling Kathleen Battle’s high-maintenance offstage personality with her artistry in performance. Her soprano was an instrument of diamantine purity, her musicality above reproach, her temperament irresistible in glittery—never tragic—roles of Handel (Semele, Cleopatra), Rossini (Rosina), and Richard Strauss (Zerbinetta). Leaving the agita in the wings, Battle regaled blissed-out fans with endless pleasure. And then she was gone. Eight years ago, in 2016, Volpe’s successor Peter Gelb “unfired” Battle, welcoming her back to the fold for a concert entitled Underground Railroad: Spiritual Journey, with piano accompaniment. This spring, she’s back again, at 75, bearing Purcell, Schubert, Mendelssohn, Fauré, Villa-Lobos, and Rodrigo, as well as selected spirituals—intimate repertory for the Met’s 3,500-seat cavern, but then, Battle’s assisting artists are Bridget Kibbey, harp, and Chico Pinheiro, guitar, and in the best hands, sound design is a subtle art. —Matthew Gurewitsch