Next, of this mind heaven is the body, light the form, viz. this sun. And so far as this mind extends, so far extends heaven, so far extends the sun. If they (fire and sun) embrace each other, then wind is born, and that is Indra, and he is without a, rival. Verily a second is a rival, and he who knows this, has no rival.

In plain words: The mind has heaven as its body and the sun as its light. It reaches as far as heaven and the sun. When fire and sun come together, wind is born, and the wind is Indra, king of the gods, who has no rival. Rivals only exist when there is a second, so whoever understands this has no rival.