It is often said that the path of Tantra is superior to the path of Sutra, but to understand why this is so we need to engage in a precise study of both Sutra and Tantra; otherwise our statements about the superiority of Tantra will be mere words.
Moreover, if we do not study both Sutra and Tantra well, we shall find it difficult to understand how to practice the union of Sutra and Tantra, and then there will be a great danger of our either rejecting the practice of Tantra or ignoring the practice of Sutra.
The teachings of Tantra, or Secret Mantra as it is sometimes called, are the rarest and most precious of Buddha’s teachings. It is only by following the path of Secret Mantra that we can attain enlightenment, or Buddhahood.
Why can we not attain full enlightenment just by practicing the paths of Sutra? There are two main reasons. First, to attain Buddhahood we need to accomplish both the Truth Body and the Form Body of a Buddha.
Although Sutra teachings present a general explanation of how these two bodies are accomplished in dependence upon the stages of the path of wisdom and method, they do not give precise explanations of the actual direct, substantial causes of these two bodies. The direct, substantial cause of the Truth Body is meaning clear light, and the direct, substantial cause of the Form Body is the illusory body. These are explained only in Secret Mantra.
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 – the subtle dualistic appearances associated with the minds of white appearance, red increase, and black near-attainment.
These three minds become manifest when our inner winds dissolve within the central channel during sleep, during the death process, or during completion stage meditation.
Although these minds are subtle minds they are nevertheless contaminated minds because their objects – the appearance of space pervaded by white light, the appearance of space pervaded by red light, and the appearance of space pervaded by darkness – appear as inherently existent.
These appearances of inherent existence are subtle dualistic appearances, and very subtle obstructions to omniscience. Because Sutra teachings do not explain how to recognize the subtle minds of white appearance, red increase, and black near-attainment, Sutra Bodhisattvas are unable even to recognize the subtle dualistic appearances associated with them, let alone abandon them.
In general, dualistic appearance is the appearance to a mind of both its object and inherent existence. All the minds of living beings, with the exception of the exalted awareness of meditative equipoise of Superior beings, have this appearance.
A direct realization of emptiness with a gross mind does not have the power to overcome the subtle dualistic appearances associated with the minds of white appearance, red increase, and black near-attainment.
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 Secret Mantra, anyone who wishes to attain Buddhahood definitely needs to enter this path.