Knowing life is impermanent and human birth is precious, it is most unfortunate that many practitioners have great faith in tantra but know almost nothing about its views and ideas. This is why I have decided to give an overview of the Vajrayana first. As for the actual practice, once genuine renunciation and bodhicitta are generated, we can begin to learn some of the practices of the generation stage and the completion stage without marks, that is, the practices associated with Mahamudra and the Great Perfection. The practice of the completion stage with marks mainly refers to practices known collectively as “winds, channels, and essences”; it is a rather complicated system of practices which we hardly employ nowadays. Naturally, one should not assume the preliminaries are no longer necessary now that one can hear the tantric teachings.
~Depicted from GATEWAY TO VAJRAYANA PATH - A Compendium of the Vajrayana