When the violinist Robert McDuffie asked Philip Glass to compose him a companion concerto to Vivaldi’s Four Seasons, Glass responded with a work with no clues among its four movements as to where winter, spring, summer or autumn can be found – listeners are left to decide for themselves. It certainly adds to the fun of The American Four Seasons, played with infectious enthusiasm by Gidon Kremer and borne along by the driving momentum of the spirited Lithuanian players. Giya Kancheli’s ethereal Ex Contrario, for violin, cello and orchestra, is a complete contrast, as calm and beautiful as the surface of a deep, slow-moving river.