Tantra
The teachings of Tantra are the rarest and most precious of all Buddha's teachings. It is only by following the path of Tantra that we can attain enlightenment.
Why can't we attain full enlightenment just by practising the paths of Sutra? There are two main reasons. First, to attain Buddhahood we need to accomplish both the mind and body of a Buddha.
Although Sutra teachings present a general explanation of how these two are accomplished in dependence upon the stages of the path of wisdom and compassion, they do not give precise explanations of the actual substantial causes of them. The direct cause of the mind of a Buddha is the realization of meaning clear light, and the direct cause of the body of a Buddha is the realization of the illusory body. These are explained only in Tantra.
The second reason why Sutra paths cannot lead us to full enlightenment is that Sutra teachings do not present methods for overcoming the very subtle obstructions to omniscience.
A direct realization of emptiness with our normal gross mind does not have the power to overcome the subtle dualistic appearances associated with subtle levels of mind.
The only way to abandon these subtle dualistic appearances is to realize emptiness directly with a very subtle mind of clear light. Since the methods for manifesting and using the very subtle mind of clear light are explained only in Tantra, anyone who wishes to attain Buddhahood definitely needs to enter this path.
Tantra is sometimes called the 'Attachment Vehicle' because, instead of trying to abandon attachment immediately, practitioners of this vehicle use attachment as an aid to generating spontaneous great bliss, with which they then meditate on emptiness.
The gateway to practising Tantra is to receive an empowerment
which is explained here.
