Taoist Sexual Alchemy

Purify your heart, clean your thoughts, curtail your appetite and conserve the semen.

If thoughts are durable, so too will be the semen; if the semen is durable, so also will be the power; if the power is lasting, the Spirit will be as well.

The power of the kidneys is located under the symbol of Water. When the impulses are roused, it flows downwards, goes outward, and produces offspring. When it is directed back by the power of thought, filtering upward to the crucible of the creator, it refreshes and nourishes heart and body, it is the reflux method. - Secret of the Golden Flower