Gustav Holst shared with Olivier Messiaen (yesterday’s composer) a deep interest in the ideas and philosophies of non-Western religion. Holst, however, went so far as to learn a bit of Sanskrit! His dual devotion to English folk song and Hindu literature, as well as several occasional “teaching” pieces written for his position at St. Paul’s Girls’ School, made for a strangely varied body of work. Holst’s most famous pieces, however, is “The Planets,” a suite of seven orchestral movements arranged by astrological association (another of Holst’s pet interests). While often pegged as a musical conservative, Holst actually paid close attention to modern music as it was imported off the continent. In 1909, Holst attended the London premiere of Debussy’s “Three Nocturnes,” including the “Sirens” movement, whose innovative off-stage female choir may have inspired this work.