Twofold certainty

The panditas of Vikramashila would present the classification of the doctrine by means of the twofold certainty (Tib. ངེས་པ་གཉིས།): establishing the certainty that what was being taught had actually been spoken by the Buddha; and establishing the certainty that what was being taught was the genuine and sublime dharma. In this way they established the authenticity of both the teacher and the teaching. While the teaching style of Nalanda has been maintained down to the present day, the teaching style of Vikramashila no longer exists within Tibetan Buddhism.