To him he replied: Prajāpati, the Lord of creatures, desiring progeny, practiced austerity. And having practiced austerity, he created the pair: Rayi and Prāṇa. These two — he said — will produce creatures in manifold forms for me.

Here the creative principle is revealed. Prajāpati, the cosmic intelligence, desires manifestation. But before creating, he practices tapas — austerity, concentration, self-limitation. This is a profound principle: creation requires first contraction.

From tapas emanates the mithuna, the cosmic pair: Rayi (matter, the moon, food) and Prāṇa (spirit, the sun, life). This duality is the foundation of all manifested existence. As the Haṭha Yoga Pradīpikā says, the entire universe is composed of energy (śakti) and consciousness (śiva).

Rayi derives from the root rā — “to give, to bestow.” It is the feminine principle, receptive, nutritive. Prāṇa is the masculine principle, active, illuminating. Together, in their union, they generate the multiplicity of forms.

For the yogī, this has a practical meaning: our body is the result of this cosmic duality. The practice of prāṇāyāma is the attempt to harmonize these two principles within ourselves.