“My time will come.” This, the most famous quote from Gustav Mahler, wouldn’t seem apt for the music of Leonard Bernstein. His time was now, over and over, whatever decade from the Forties to the Eighties one is talking about. But there were dips in his meteoric trajectory, and Mass, which opened Kennedy Center in 1972, was a drastic one. Reviews weren’t merely dismissive; they expressed embarrassment for the composer, who leapt from his pedestal as an icon of classical music into the arms of hippies, flower children, and the Age of Aquarius. The work owed a distressing amount to Hair, the musical, and less obviously to Benjamin Britten and Bernstein’s own earlier works. As a spectacle, it combined the liturgy of the Latin Mass with episodes of the mob (updated with tie-dye, peasant blouses, and afros) jeering at the Church and belief in God generally. Bernstein wasn’t, shall we say, the most obvious candidate for a work of Christian devotion, and with eyes averted from the schlocky libretto -- crafted by Broadway baby Stephen Schwartz, who was young but no wunderkind-- the composer’s admirers chose to bury Mass as an ecumenical mess. The prevailing wisdom was that this, too, shall pass.