Zhentong isn't Cittamātra
For some reason, those unfamiliar with the zhentong presentation tend to associate it with the Cittamāra ("Mind Only" or "Mentalist") system, as if Madhyamaka was only divided into Svātantrika and Prasaṇgika. According to the Jonangpa, this is a case of mistaken identity.
Perhaps one of the most intriguing developments in the historical narrative on the Tibetan zhentong tradition is the Jonangpa categorical situating of the Cittamātra system in relation to the other major philosophical "schools" of Indian Buddhism.
While the Cittamātra is generally associated with the final turning set of sūtra discourses and the śastra literature attributed to Maitreya, Asaṅga and Vasubandhu, the Jonangpa challenge this assumption as a conflation of Cittamātra doctrines with the Great Madhyamaka. To begin, they make the common distinction between (a) the Cittamātra system that asserts sensible phenomena to be real (rnam bden pa’i sems tsam) and (b) the Cittamātra system that asserts sensible phenomena to be artificial (rnam rdzun pa'i sems tsam). They consider the former to have been the earlier system historically, while the latter arrived in conjunction with the Madhyamaka tradition in India.
Although the Great Madhyamaka system is considered to have arose much later, it was confused with the Cittamātra in India and later in Tibet. The Jonangpa describe this as a whispered lineage (nyan brgyud) that was transmitted from ear-to-ear from Indians to Tibetans. That is to say, it was an esoteric line of transmission that emphasized contemplative insights in contrast to analytical investigation. Its said that this line continued through the Kashmiri scholar Sajña on to the Tibetan figure Tsen Khawoche up to Dolpopa.
Doctrinally, the zhentong tradition is in alignment with the Cittamātra system that asserts sensible phenomena to be artificial, asserting that the perfected nature (pariniṣpanna, yongs grub) and nondual pristine awareness are truly established (giving reason for conflation). In contrast, the Cittamātra system that asserts sensible phenomena to be real (rnam bden pa) also asserts the momentary awareness to be real in absolute terms, and that the relational nature (paratantra, gzhan dbang) is truly established.
To take this emphasis on the three natures a step further, the Jonangpa make the case that since the three natures are found within many of the core sūtras including the Chapter Requested by Maitreya in the Prajñāpāramitā, the Laṅkāvatāra-sūtra, and the Saṃdhinirmocana-sūtra, they makeup a central doctrine of the Zhentong Madhyamaka. In order to reassert this point, Dolpopa writes with this argument in mind,
If for instance someone were to say, ‘Because the middle turning is Madhyamaka and the final turning is Cittamātra, the middle turning is definitive in meaning and the final turning is provisional in meaning; this invalidates your position.’ This is extremely irrational because (a) there is no scripture or reasoning whatsoever that suggests that the final turning follow the core texts of the Cittamātra and because (b) [the final turning] teaches what is beyond the Cittamātra, teaches the meaning of the consummate Great Madhyamaka, and teaches in accord with the meaning of the consummate Vajrayāna.
In sum, the Jonangpa do not equate the core doctrine or the seminal sūtras associated with the final turning with the Cittamātra, and in fact include works from the Prajñāpārmitā genre in this grouping based on the logic that these texts contain discussions on the three natures.
As you might expect, there is much more to say about this. Your comments are most welcome.
1. An interesting division here is between those considered to be of the Cittamāra system that asserts actual existence (dngos smra ba'i sems tsam) and those who explicate discerning cognition (rnam rig smra ba). The former is associated with Rangtongpas while the latter is associated with Zhentongpas.
3. This is quoted in Ngag dbang Blo gros grags pa. Rgyu dang 'bras bu'i theg pa mchog gi gnas lugs zab mo'i don rnam par nges pa rje jo nang pa chen po'i ring lugs 'jigs med dgong lnga'i nga ro, 1, 60. In Blo gros grags pa’i Gsung ‘bum, 'Dzam thang.