'Such is the greatness of it (of Brahman, under the disguise of Gâyatrî); greater than it is the Person (purusha). His feet are all things. The immortal with three feet is in heaven (i.e. in himself).'

In plain words: The quoted verse says the Person, the Supreme Being, is even greater than all this. All created things are only one quarter of him, and the other three quarters are immortal, beyond this world.