For that heart there are five gates belonging to the Devas (the senses). The eastern gate is the Prâna (up-breathing), that is the eye, that is Âditya (the sun). Let a man meditate on that as brightness (glory of countenance) and health. He who knows, this, becomes bright and healthy.

In plain words: The heart is pictured as having five doorways, guarded by the senses. The eastern door is the in-breath, which is linked to the eye and the sun. Whoever meditates on it this way becomes bright-faced and healthy.