Eighteen Esoteric Instructions of the Mental Class. As stated in Longchenpa, Treasury of Spiritual and Philosophical Systems, pp. 357 8, they are {rig pa'i khu byug}, {rtsal chen sprug pa}, {khyung chen lding ba}, {rdo la gser zhun}, {mi nub rgyal mtshan nam mkha' che} [which five constitute the five earlier translations made by Vairochana. {rtse mo byung rgyal}, {rnam mkha'i rgyal po}, {bde ba 'phrul bkod}, {rdzogs pa spyi chings}, {byang chub sems tig}, {bde ba rab 'byams}, {srog gi 'khor lo}, {thig le drug pa}, {rdzogs pa spyi spyod}, {yid bzhin nor bu}, {kun tu rig pa}, {rje btsan dam pa}, and {sgom pa don grub}- which thirteen constitute the later translations made by Vimalamitra, Ngak Jnana Kumara, and Yudra Nyingpo.