We all know that the Buddha transmitted the Dharma to followers according to their capacity and guided them on the path step by step. The Outer Tantra, having also empowerment, the practice of generation stage and so forth, is part of Vajrayana, but it lacks the view of the Inner Tantra. Hence, practitioners can only visualize themselves as they are in the present world (though sometimes they also visualize themselves as buddha), then visualize the buddha and the yidam in front and recite mantras. The Outer Tantra offers many ways to recite mantras; it is of the view that one can attain buddhahood by way of mantra recitation.

When followers of the Outer Tantra practice in retreat, they are very particular about personal hygiene, keeping a vegetarian diet, and washing themselves three times a day; the focus is on one’s conduct, and they do very well in this respect, but less so in the practice. Actually, the more one is fixated on the particulars of behavior, the more likely problems in practice will surface. The higher the state one reaches in practice, the more likely some improprieties may appear in one’s conduct. Naturally, impropriety does not mean wrongdoings such as killing, stealing, lying and so on are casually tolerated. You can get a better understanding of this from the life stories of the eighty great siddhas of ancient India.

- Quote from Gateway to the Vajrayana Path, "The Parable of a Black Snake"