Tibetan Buddhism derives from the confluence of Buddhism and yoga which started to arrive in Tibet from India briefly around the late eighth century and then more steadily from the thirteenth century onward. Indian Buddhism around that time had incorporated both Hindu yogic and tantric practices along with the classical teachings of the historical Buddha who lived around 500 B.C.E. It acknowledged that there were two paths to enlightenment (complete transcendence of identification with the personal ego). One path was that taught in the sutras according to the historical teachings. The heart of sutra practice was based on morality, concentration, and wisdom (not identifying with the personal ego). The other path, which has become the cornerstone of Tibetan variations, was tantric. This practice blended the sutra teachings with techniques adapted from Hindu systems of yoga and tantra.
Tantric systems transform the basic human passions of desire and aversion for the purpose of spiritual development. Rather than denying such primal urges, tantra purifies them into wholesome and helpful forces. It is very much like trying to deal with a wild horse charging towards you. One way is denial: put up your hands and shout out, "stop, stop!" Probably you will be bowled over by the animal. A cleverer approach is to step aside and then jump on its back as it charges past you. In such a case, you have a chance to start coaxing it to move in certain directions, and over time you may be able to direct it into a stable. Truthfully, one needs some skill in both self-control and acceptance if one is to be successful with tantric work.
Tibetan Tantra (also known as the Vajrayana) incorporates the major aspects of both the Hinayana and Mahayana Buddhist teachings. It is basically an esoteric extension on these themes. Hinayana and Mahayana are two schools of Buddhist practice that have basically similar goals and techniques but somewhat differing philosophies. For instance, Theravadin Buddhism (known for its Vipassana meditation) is a Hinayana teaching and Zen Buddhism is a Mahayana teaching. Tantra itself has various schools which can be grouped by the relative emphasis they place on working with exoteric and esoteric practices.
The tantric path includes the following steps:
lamrim (stages of the path)
These are indispensable topics for reflection and contemplation and also the meditations and activities that should naturally follow on from them. The Lamrim embodies the necessary prerequisites for tantra. It is set out as a progressive set of steps.
Meditation on emptiness is integral throughout this practice. A simple way to understand emptiness is as follows. In the physical world, the personal ego has a relative span and will cease when the body does. So relative to it, the soul, or Enjoyment Body, is much more important since it will continue on after death. Thus saying the ego or self is empty means it is better to ground awareness in the soul and experience the ego as a garment, rather than only experiencing the ego and having no real connection with the soul. Thus emptiness is a statement about priority—we should consider the bigger context of our experience in order to live more wisely and wholesomely.
The same principle of emptiness applies as progressively higher levels of reality are experienced. Hence, when the Enjoyment Body, or soul, becomes a living reality for the meditator, she or he continues to take it as relatively real and keeps grounding awareness in the encircling context. The context, or deeper level, for the soul is the Truth Body (which is just a subtler version of the soul). So as a meditator realizes the Truth Body, the Enjoyment Body becomes the new object for meditation on emptiness.
To recapitulate the entire process: at the beginning we have a body and mind (the personal ego or self). Next an astral body (Enjoyment Body) is developed and it is as if the physical body and personal ego have become the "body" and the astral body has become the "mind". Next a very subtle body (Truth Body) is developed and the final result is that the astral body becomes the "body" and the Truth Body becomes the "mind". At each stage of this sequence, the "body" is subjectively experienced as being empty by the "mind".
What is the experience of emptiness like? At the beginning level of physical body and mind, emptiness means that one does not identify with any experience whatsoever. Any sight, sound, or other sense is recognized and honored for what it is, but it is not clung to. Similarly, all thoughts and feelings are also taken in this way—as being real and valuable, but not as being in one's possession so that one does not cling to the experience of them. It is as if all experiences, whether external (in the world "out there") or internal (inner thoughts, hopes, feelings, and desires), are viewed as clouds passing by. The reality is the sky which the clouds float by in. And if the sky is noticed, it too is taken as just another cloud wafting by. The result of this amazing relation to one's experience is an enormous sense of relief, peace, and clarity. At first it seems that one will die if one doesn't cling to experience, but after a while it becomes apparent that one continues to live on anyway. We are more than just the experiences that we engage in.
The same process applies at progressively more subtle levels of experience. The contents of experience become more and more amazing and wonderful (to our normal way of thinking) but the most skillful way of relating to them still remains the practice of mindfulness (emptiness meditation). So once a yogi creates an astral body and can experience reality at that level, he or she works at non-identification with the astral body. And similarly, once a Truth Body exists, meditation on its emptiness continues as well.
This is also a very advanced teaching whose end result is the same as for the tantric path. Its techniques and emphasis are a bit different. Primarily, Dzogchen underscores direct perception of the fundamental nature of reality. So instead of working to create higher energy bodies such as the astral body, it seeks to ground awareness directly back into the Truth Body. And as mentioned above, this Body reaches the limits of human experience and expression so that its subjective experience is one of all-encompassing emptiness. That is, there is nothing more to be said about this level with the common tools of human experience—words and emotions. The main practice is similar to Zen meditation and consists of holding a constant perceptual openness to all experience. For such practice to lead to subtler insight, however, a Dzogchen practitioner needs to receive empowerments (transmission of spiritual energy) from a qualified teacher. These act somewhat as a self-correcting guidance system to help a meditator to gradually open to the deeper dimensions of reality. Some Dzogchen meditations are similar to tantric visualization and energetic practices. The basic prerequisites for Dzogchen are similar to Tantra.