And verily this Self is the lord of all beings, the king of all beings. And as all spokes are contained in the axle and in the felly of a wheel, all beings, and all those selfs (of the earth, water, &c.) are contained in that Self.

In plain words: This Self is the ruler and king of all beings. Just as all the spokes of a wheel are held together by its hub and rim, every being and every world is held together in this one Self.