That Brahman (mind) has four feet (quarters). Speech is one foot, breath is one foot, the eye is one foot, the ear is one foot—so much with reference to the body. Then with reference to the gods, Agni (fire) is one foot, Vâyu (air) is one foot, Âditya (sun) is one foot, the quarters are one foot. Thus both the worship which has reference to the body, and the worship which has reference to the Devas, has been taught.

In plain words: Brahman, seen as mind, has four parts like four feet. In the body they are speech, breath, sight and hearing. In the outer world they are fire, air, the sun and the directions.