He who does not know that indestructible being of the Rig-Veda, that highest ether-like (Self) wherein all the gods reside, of what use is the Rig-Veda to him? Those only who know it, rest contented.

In plain words: What good is the Rig Veda to someone who does not know the eternal, sky-like Self it speaks of, the highest one in whom all the gods live? Only those who know this Self find real contentment.