The unabridged, annotated English translation of this Tibetan treatise is preceded by a general introduction situating the author-a pivotal figure in what would become the Nyingma school of Tibetan Buddhism-and his work in historical and doctrinal context. The detailed annotations provide elucidating comments as well as crucial references to the numerous texts quoted by the Tibetan author. This book makes this groundbreaking Tibetan work on meditation accessible in English and opens fascinating windows on early forms of contemplative practice in Tibet.