After you've received empowerment into the practice of a particular awareness-being, or yidam, the form of this awareness-being will spontaneously arise out of the state of emptiness when you engage in practice. The form of the awareness-being will also arise in your dreams – maybe even in the steam that arises from your cup of coffee. It depends on the intensity of your devotion. There is no process – it simply happens because you have the key; and the key is the Tantric text or the awareness-spell which is sung to instigate this arising. Your experience of emptiness is the oven where the bread of your vision bakes itself. The empty state is the perfect environment for endless vision to arise.p116, Wearing the Body of Visions, Ngakpa Chögyam, Aro Books, 1995, ISBN 1-898185-03-4