Tib., snying thig, snying tig: Heart Essence, Quintessence
Based on the Tibetan terms snying (heart, innermost core) and thig, thigs or thig le (essence, drop), the literal translations of the term nyingtig range from heart essence and innermost essence to innermost spirituality and quintessence.
What all these terms refer to, is a category (or class) of teachings - and its related texts - that form an essential part of what is better known as Dzogchen, the 'Great Perfection' lineage of teachings at the apex of Vajrayana (also known as 'Esoteric Tibetan Buddhism' or 'Tibetan Tantra').
In a general sense, nyingtig refers to the complete Instruction Section of the Great Perfection teachings, subdivided into 51 sections. However, once this body of teachings had been divided into four parts - the Four Cycles of Nyingtig - the term nyingtig was often used as referring especially to the highest and most secret of these four cycles: the Innermost Unexcelled Cycle of Heart Essence (yang gsang bla na med pa'i snying thig gi skor).
All Nyingtig teachings, whether or not based on original (Indian) texts, on continuous oral transmission or on hidden and revealed terma treasures, are traced back in time through a number of Indian teachers and adepts ranging from Garab Dorje and Manjushrimitra via Sri Singha to Padmasambhava and Vimalamitra; with the latter two actually passing the tradition into Tibet.
Based on the written and oral transmissions of these adepts, various strands (lineages) and collections of Nyingtig teachings came into being until they were combined and unified in the 14th century by Longchenpa and his close friend Rangjung Dorje (the 3rd Karmapa).
After a period of decline, the Nyingtig tradition was once more revitalized by the 18th century visionary Jigme Lingpa, and has since then continuously grown in importance; especially through the efforts of the 19th century, non-sectarian Rimed movement.
The various collections of texts, transmission lineages and cycles of teachings are known as
Practitioners of the Nyingtig teachings are variously known as snying thig pa, snying thig snying po'i rnal 'byor ma or snying thig snying po'i don la spyod pa'i rnal 'byor pa, terms that remind us that we are dealing here with the type of independent, shamanic yogin (Tib., rnal 'byor pa) and yogini (Tib., rnal 'byor ma) of the Old School (Tib., sngags rnying ma) rather than with the domesticated nuns or monks of most later New School (Tib., sngags gsar ma) monasteries.