“Oh as I was young and easy in the mercy of his means, / Time held me green and dying / Though I sang in my chains like the sea.” Reading Dylan Thomas’s meditation on childhood blissfully unaware of all-devouring Time, it’s not hard to imagine a luminous orchestral setting for light tenor or baritone—a pendant, perhaps, to Samuel Barber’s Knoxville: Summer of 1915, for lyric soprano. Well, as a composer just starting out, John Corigliano (who turned 88 in August, a year for every key on the piano) heard in his mind’s ear the sounds not only of a soloist but also of a chorus, and that’s how he wrote it down. Might that suggest that Thomas’s vision belongs not to one child but to all children? (If so, consider the parallels to Heaven as conjured up in Mahler’s Third and Fourth Symphonies.) The Oratorio Society of New York pairs Corigliano’s hallucinatory cantata with, of all things, Mozart’s Great Mass. Written in the far from celestial key of C minor, the Mass dates to the period of Mozart’s marriage to Constanze Weber, not his first choice of mate but in the long run the right one. He had no commission for the mass, and he never completed it. (Some say he undertook it in fulfillment of some personal vow.) Yet the fragment stands as one of the supreme sacred works in the canon. Which of the many performing editions will be played on this occasion has not been announced. Kent Tritle, the doyen of sacred music in the Big Apple, conducts. —Matthew Gurewitsch