Coming so soon after the Symphonia — and from a composer now in his nineties — this was an extraordinary flourish of orchestral rejuvenation. The pattern is similar to that of the intervening Asko Concerto: music of one kind, often using rather full resources, is interleaved with episodes of different sorts for different ensembles. Among the latter are inventions for flutes plus clarinets and for single reeds, a slowly revolving brass object and a passionate strain from strings. The abiding spirit, however, is that of the rapid, shimmering main music — rain music, recalling a poem by William Carlos Williams in which love is seen, like showers, to “bathe every open object of the world.” Writing to a commission from the Boston Symphony, Carter fittingly dedicated the score to his wife, Helen.