Vajrayana comprises the outer and the inner tantras. Tantra may sometimes be talked of as if only texts containing tantric teaching but in fact tantra means ‘continuation’ and this alludes to the fact that although all phenomena are essentially void they still continue to manifest.
Tantra takes the realization of the emptiness of all phenomena (which is the fruit of sutra) as its base or starting point.
From this view instead of relative existence being something to be avoided at all costs, through the passions shunned by sutra it actually provides the energy required for progress towards realisation.
All the tantras whether inner or outer employ visualisation as the principal skilful means, or to be more precise, envisionment.
The outer tantras commence at the level of external conduct to purify thought and action in preparation to receive wisdom.
Kryatantra and Upatantra are both referred to as the Path of Purification. Yogatantra and the three inner tantras are the Path of Transformation.
The inner tantras also start from the realisation of the emptiness or voidness of all phenomena but mainly use inner yoga, working on the tsa lung system of the practitioner’s body to transform his/her whole dimension into the dimension of the realised being visualised in the practice.
So tantra is based on pure vision and is also motivated by the aspiration to free all sentient beings and oneself from delusion as quickly as possible but through ‘skilful means’: Relative truth becomes the path by regarding phenomena as the limitless display of primal wisdom.
This is progressively more directly experienced within each of the six classes of Vajrayana vehicles.
The Hinayana and Mahayana are known as ‘causal vehicles’ as one is accumulating merit and wisdom, which will reap their fruit in Enlightenment and therefore working at a "causal" level.
The Vajrayana is described as the ‘resultant vehicle’ as through skilful means it starts from the premise of realization.
In the causal vehicles one recognises the nature of mind as the cause of Buddhahood; in the resultant vehicle one regards the nature of mind as Buddhahood itself.
Mahayana recognises Buddha nature as being potential in every being Vajrayana considers Buddhanature to be fully present as wisdom or pristine awareness, the fundamental nature of Mind. One therefore ‘only’ has to reveal or realise it!
Empowerment from an authentic qualified teacher is essential for all Vajrayana practice.
The Buddha taught these methods in a manifestation body as well as by other sambhogakaya manifestations.
Transmission of tantra is originally received through the manifestation of the sambhogakaya appearing to a master who has sufficient clarity to perceive that dimension and the method of practice in tantra is also that of manifestation.
The practitioner is initiated into this practice by the master through visualisation and the reintegration of one’s subtle energies so that he/she follows the example of the original transmission manifesting as the deity entering into the pure dimension of the mandala.
The practitioner realises the sambhogakaya itself, transcending the mundane world of gross elements which are experienced as their essences.
Upon death the practitioner enters the dimension of light and sound which is the essence of the elements and in that state of being is able to continue to benefit sentient beings as the deity whose practice has been accomplished during lifetime.