As spokes in the nave of a wheel, everything is fixed in Prâna, the verses of the Rig-veda, Yagur-veda, Sâma-veda, the sacrifice, the Kshatriyas, and the Brâhmans.

In plain words: Just as spokes are held in the hub of a wheel, everything rests on Prana: the sacred Vedas, the rituals, the warriors and the priests.