When we die, we get down to a very, very subtle state like a mind of a Buddha.
And then we have a period of time in between births, which is known as the bardo (bar-do) in Tibetan, and in that bardo period we have a subtle appearance.
And then when we are born, starting with the moment of conception, we have a grosser appearance.
Three bodies of Buddha in the process of going to sleep:
When we go to sleep, there’s a transformation – the mind gets very subtle.
Then when we dream, we have a very refined, special type of appearance in the dreams.
And then when we wake up, we have a grosser appearance, which comes from that subtle appearance.
Highest Yoga tantra practice is the practice of developing these different bodies of a Buddha
Motivation: compassion for all the sentient beings. We have a strong desire to help others.
Generation stage. Working with our imagination. We imagine that our energy gets more and more subtle and concentrated and then takes on a more subtle appearance and then a gross appearance. We then imagine that we arise in a subtle form, for instance as a seed syllable, and then in a grosser form, namely that of a Buddha-figure, a yidam.
Complete stage. Working with the subtle energy system of the body. We dissolved the grosser levels of mind and energy-wind and now have an access to the subtlest clear-light level. We then generate from that level the subtle forms known in some anuttarayoga systems as illusory bodies. From these, we generate grosser forms, known as pathway emanation bodies.
The practice of Anuttarayoga is characterized by the practice Deity Yoga and also through various subtle body yogas (such as the six Dharmas of Naropa), to generate great bliss and attain the subtle clear light (luminous) mind.
Practiced in Tibetan Buddhism and Newar Buddhism.
The practice of Anuttarayoga Tantra in the Vajrayana tradition of Buddhism is characterized by the requirement of Empowerment from a qualified Guru, usually a Lama, use of ritual techniques, and the practice of various meditative and subtle Body yogas, to effect personal transformation and to attain Enlightenment through the realization of the Mindstream as a Meditational Deity, or a Yidam.