'The altar, O Gautama, is man; the fuel the opened mouth, the smoke the breath, the light the tongue, the coals the eye, the sparks the ear. On that altar the Devas offer food. From that oblation rises seed.

In plain words: A man is pictured as a sacred fire, with his mouth, breath, tongue, eyes and ears as its parts. The gods offer food into him, and from that comes the seed of new life.