Three types of investigation
- the demonstration of what is evident (mngon gyur) is not invalidated by direct perception (mngon sum),
- the demonstration of what is hidden (lkog gyur) is not invalidated by inference (rjes dpag),
- the demonstration of what is extremely hidden (shin tu lkog gyur) is not contradicted (internally) by previous or later statements.
- Translation from: Douglas S. Duckworth, Mipam on Buddha-Nature, The Ground of the Nyingma Tradition, p.221n55
- The third point is sometimes abbreviated as the criteria of scriptural authority. See Mipham Rinpoche: The Adornment of the Middle Way, p.393, n115.
- Mipham Rinpoche: The Adornment of the Middle Way, p.375: "But here we have the perfect teachings of the Tathagata, excellent in their beginning, middle, and end. These are like gold that is smelted, cut, and polished; they can withstand threefold examination and are not faulted by perception, inference, or verbal inconsistency."