“A symphony must be like a world,” Mahler once said. “It must contain everything.” The statement is commonly taken to apply with special force to his epic Symphony No. 3, which a Georg Solti could dispatch in about 90 minutes, while a Leonard Bernstein might linger an extra 15. While in the creative stage, Mahler thought of the whole as “A Midday Dream in Summer” and had working titles for each of its six movements. The first told of the coming of Pan, pagan god of the natural world. Each of the other movements was taken to convey a message—from the flowers of the field, from beasts of the forest, from man, from the angels, and from Love itself. Like several other Mahler symphonies, this one blossoms into song. The uncanny nocturnal stillness of the fourth movement includes a setting to mystic verse from Nietzsche’s Thus Spake Zarathustra, sung by a contralto soloist. The fifth movement, featuring children’s and women’s voices, paints heaven as seen through the eyes of a child—a motif Mahler would return to, minus the disquieting ambiguities present here, in his Fourth Symphony. The singing in the unhurried, enormous final movement—duration, around 30 minutes—is purely instrumental. Leave it to Captain Daniel Harding, the commercial pilot for Air France who moonlights as a conductor in international demand, to stick the landing. —Matthew Gurewitsch