[To return to the beginning of this biographical series, click here]
The Lo rgyus rin chen phreng ba (p. 70) does confirm that it was with this master that Klong chen pa studied the Sūtra of the Illusionary Net (Māyājāla, mDo sgyu 'phrul) and the Sems phyogs, i.e., the Mind Section (Sems sde) of the rDzogs chen, or, more generally, the rDzogs chen of the unbroken oral tradition (bka' ma). This is of particular interest insofar as gZhon nu rdo rje also appears as one of our author’s direct masters in the lineage that the latter presents at the beginning of his manual of practice of the Tantra of the King Creator of All Things, the Jewel Nave (Rin chen gru bo, no. 160).
Perhaps it should be recalled that the Tantra of the Creator King of all things is the fundamental Tantra of the Mind Section (rDzogs chen sems sde), and that the Jewel Nave is the only preserved text that our author devoted to the Sems sde as such.
We could, through an investigation of the transmission of the Sems sde, try to find out a little more about this gZhon nu don grub. Indeed, if he does not appear under this name in the Deb sngon, the same cannot be said of his master, Bo dong Kun dga’ don grub (1268-1328, according to Blue Annals, p. 974, where he is given the name of “omniscient,” kun mkhyen). He is one of Karma pa Rang byung rdo rje’s masters (Blue Annals, p. 490, “Kun dga' don grub of sNye mdo”). He appears both as a Kālacakra scholar, a master of ancient and modern tantras, and as a scholastic scholar of Ku ma rā dza’s generation (they are mentioned side by side in Blue Annals, p. 197, where it appears that they were only two years apart). He was also (Blue Annals, p. 702) a disciple of Siddha U rgyan pa (1230-1309), also a master of Karma pa Rang byung rdo rje. Kun dga’ don grub is furthermore (rDzogs pa chen po snying thig spros bcas kyi dbang lCe btsun gyis mdzad pa, in Bi ma snying thig, p. 197) the one who transmitted Bi ma snying thig in the lineage of lCe btsun to Karma pa. It follows that gZhon nu don grub was probably not only versed in the Mind Section (Sems sde), but also in the Quintessence (sNying thig) of the Instructions Section (Man ngag sde). It is therefore highly probable that he at least conceived the synthesis of Tantrism in the light of rDzogs chen later developed by Klong chen rab ’byams in his Treatise Dispelling the Darkness of the Ten Directions (Phyogs bcu'i mun sel).
Unfortunately, an examination of the passages in the Deb sngon devoted to Bo dong Kun dga’ don grub does not allow us to know much more about gZhon nu don grub, except to place him in a milieu of Kālacakra scholars more or less gravitating around Karma pa Rang byung rdo rje, which is very likely. The gTer ’byung rin po che'i lo rgyus (p. 123) is a bit more specific about the teachings Klong chen rab ’byams received from this master, since, to the mDo sgyu ’phrul and the Sems phyogs, it adds the Guhyasamāja (ancient or modern, this is not specified), the gSang ldan (Ārya-Mañjuśrīnāmasaṅgītisādhana), the gTsug dgu, and the sByong rgyud (Sarvadurgatipariśodha ..., etc....)
The fact that this gZhon nu don grub, in addition to its affinity with the Guhyagarbha, had a connection with the Kālacakra is very interesting. Indeed, in order to show that the Guhyagarbhatantra is a “generic” tantra, including the teachings of all three classes of “inner” tantra, Klong chen rab ’byams, in the Treatise Dispelling the Darkness of the Ten Directions, expands considerably on its visionary practices of the clear light of the completion phase. He presents them in a manner exactly in accordance with the meditations of the Thod rgal, which are characteristic of the quintessence of the Great Completion (rDzogs chen snying thig). Now, apart from the rDzogs chen, it is the Kālacakra that gives the greatest development to such visionary practices. In conclusion, we may assume that perhaps gZhon nu don grub, in his teaching, may have at least sketched this rapprochement of the Guhyagarbha with the luminous visions of the rDzogs chen, in a synthesis that Klong chen rab ’byams was to bring to fruition, after he had fully assimilated the teaching of the sNying thig with Ku ma rā dza. This hypothesis is obviously only valid until further notice and subject to the results of the analysis of the numerous commentaries on the Guhyagarbha already published.
Let us note in passing, in the same vein, that the development of the Instructions Section (Man ngag sde) of the rDzogs chen from the twelfth to the fourteenth centuries remains obscure, especially outside of the comparatively better-known stream embodied by Ku ma rā dza, Padma las ’brel rtsal, and the Karma pa Rang byung rdo rje.
Tradition has tended to erase the trace of those systems which, for one reason or another, have not survived, or at least have not acquired a dominant position. Even when these great cycles of pre-Klong chen rab 'byams’ rDzogs chen are not lost, but remain alive in the practice of present-day rNying ma pa, their past greatness is downplayed in historiography, as if they had always been, at best, of secondary importance. But in fact, those systems of Man ngag sde that have fallen into relative disuse, for example, those of the gter chos of Nyang ral Nyi ma 'od zer and Guru Chos dbang, have the great interest of presenting transitional forms which, from the retrospective point of view of the moderns, appear as the embryo of that whose completed form is only to be found in the sNying thig or in rGod ldem’s dGongs pa zang thal. Or rather, since nothing is so foreign to the traditional masters as the quasi-teleological representation of a progressive organic growth of the rDzogs chen, these cycles are given, in the rNying ma pa school, simply as less profound or less complete.
It seems that through his training, Klong chen rab 'byams must have encountered all sorts of rDzogs chen teachings, some of which included more or less developed visionary practices, but that Bi ma snying thig alone seemed to him to provide the doctrinal framework and the ultimate end of rDzogs chen.
The next section is here.
 Recall that this sūtra is in fact a huge tantra, which currently exists only in fragments (some of which are several hundred pages long); the *Guhyagarbha is supposed to be a section of it.
 Opinions that associate the rDzogs chen elements of the Ngal gso skor gsum, or the Rang grol skor gsum, or even the Chos dbyings rin po che’i mdzod, with the Sems sde, are unfounded.
 Vol. 23-36 and 71-75 of the bKa’ ma shin tu rgyas pa, mostly.
 The mKha’ ’gro snying thig and the dGongs pa zang thal, to take just two examples, are largely based on the seventeen fundamental tantras of the Bi ma snying thig, which, in this respect, provides the key. The same cannot be said of Guru Chos dbang’sSangs rgyas mnyam sbyor. But this is not a purely chronological question, as if this were only a sign of the anteriority of the Sangs rgyas mnyam sbyor: the Yang ti nag po, discovered by Dung mtsho ras pa in 1316 (?), therefore at a time when these seventeen tantrashad already appeared (whatever their origin, in the final analysis), does not seem to be closely dependent on it (but we have only gone through it rather superficially and do not have any well-formed certainty in this regard).