One of the special Great Seal ("phyag rgya chen po: mahāmudrā") teachings for which sGam-po-pa was best known was his so-called "introduction to the of Mind" ("sems kyi ngo sprod"), by which the disciple was led to confront and directly recognize the nature of his or her mind. sGam-po-pa is said to have given such Great Seal instructions sometimes not as secret Vajrayana precepts in connection with initiation and special yogic practices, but rather as a Sūtra-based Great Seal instruction, or even as a doctrine going beyond both Sūtra and Tantra. Later critics such as Sa-skya Paṇḍita (or Sa-paṇ, as he was known for short) maintained, however, that all true Great Seal instructions were Mantrayana teachings that necessitated full, formal Tantric initiation into a maṇḍala. These masters denied in general the existence of any Sūtra-based or non-Tantric Great Seal, and in particular they considered the existence of any Mahāyāna doctrine outside the classes of Pāramitāyāna and Mantrayāna to be impossible.