Consciousness is purusa, unchanging. In order to exist as a material life form it must combine with matter that is always changing, prakriti. This is a paradox. The Hindu yogic tradition uses the myth of Shiva and Shakti to explain.
They are a divine couple, lovers in the fields of creation. Shiva is the seer, purusa, never changing, and Shakti is energy, prakriti, always changing. Shakti, the lover, wants to play a game of passion and creates a world inviting Shiva, the beloved, in to join her. Shiva points out the world is always changing and he is always the same. How can he play in her creation?
“You be the center,” she replies. “You remain in your unchanging bliss and I’ll intermediate between you and the outside world. I will build sheaths through which you can experience the fun of my world while doing nothing in eternal bliss.”
Five koshas (sheaths) surround Shiva, allowing the lovers to experience passion as the embodied soul.
Weight Loss Through Yoga, Jewel in the Lotus page 69