The first movement — which lasted a solid 40 minutes on Saturday, longer than many complete symphonies — is a murky, atavistic thing that swells with melodic and rhythmic ideas that briefly surface from the primordial mass, only to shrink back time and again. After that, there are still five movements to go, gradually climbing from the wild, untameable natural world into a spiritual realm of heavenly bliss in the achingly radiant, slow final movement.