吐蕃帝國興佛運動與西藏早期中觀傳統——《大乘經纂要義》以及相關文本研究

Promoting Buddhism in the Tibetan Empire and Traditions of Madhyamaka in Early Tibet: The Summary of the Essential Points of the Mahāyāna Sūtras and Its Textual Variants

吐蕃贊普墀祖德贊敕頒《大乘經纂要義》（822），是繼墀松德贊敕頒桑耶寺建寺《第二詔書》（779）之後最為重要的吐蕃官方佛學綱要。如上兩部文獻，堪稱吐蕃帝國興佛運動的文本坐標。二十世紀三○年代以來，學者陸續發現敦煌漢文《大乘經纂要義》寫本四種。然而對其藏文文本，前輩學者久尋未得。直至近時，筆者確信地發現了敦煌藏文《大乘經纂要義》寫本五種。這一文本發現，使得筆者有幸重啟上山大峻先生以後沉寂多年的對於《大乘經纂要義》以及相關文本的語文學研究。基於《大乘經纂要義》藏漢對勘，可為更加廣泛、深入的文本比較和義理溝通架設一座橋樑。尤其值得重視的是，其與吐蕃譯師那囊‧智軍、吳‧法成等人的相關論疏以及敦煌藏文宗義文獻乃至禪宗文獻，多有可資比較、印證之處。通過這項研究，可以獲得如下兩條全新認知：（一）《大乘經纂要義》幾乎可以總攝藏傳佛教前弘期吐蕃官方認可的大乘顯教的全部義理，實以「二諦」、「三乘」之說為其核心，而以「經部行中觀」思想為其旨歸；（二）《大乘經纂要義》基於漢地論師曇曠以及吐蕃譯師那囊‧智軍所傳「大乘三宗」之說，進而依循「經部行中觀」傳規，正是吐蕃時期漢藏佛學深度交流的產物。對於中觀宗見尤其經部行中觀的依循和發揮，堪稱藏傳佛教前弘期和後弘初期大乘顯教的一個基本特徵。《大乘經纂要義》的頒行及其影響，折射了吐蕃時期大乘顯教發展史的外在約束性和內在自覺性，以及西藏早期（8-11世紀）中觀傳統的歷史連續性和教理統一性。

The Summary of the Essential Points of the Mahāyāna Sūtras (Dasheng jing zuan yaoyi, 822 CE; hereafter SEPMS) promulgated by the king of Tibet Khri gtsug lde btsan (r. 815–838) is the most important official Buddhist outline following the Second Edict (bKa’ gtsigs gnyis pa, 779 CE), which was promoted by king Khri srong lde btsan (r. 755–797). These two doctrinal treatises can be regarded as textual coordinates of the movement to promote Buddhism in the Tibetan Empire. Since the 1930s, scholars have discovered four Chinese versions of the SEPMS in the manuscripts from Dunhuang, but no Tibetan ones. Fortunately, I have recently identified five Tibetan manuscripts of the SEPMS within the Dunhuang manuscripts, providing me with the opportunity to renew the philological study on the SEPMS and related textual variants following a long period of silence concerning the topic since the research of Daishun Ueyama. Based on a comparative study of the Tibetan and Chinese texts of the SEPMS, this discovery can serve as a bridge that connects doctrine with a more in-depth and extensive textual comparison. Furthermore, it is worth noting that several points can be verified by examining the SEPMS with its textual variants, such as the related treatises (bstan bcos) written by the Tibetan translators sNa nam Ye shes sde (Nanang Zhijun, ca. 8th–9th century) and ’Gos Chos grub (Wu Facheng, ?–859), as well as the Tibetan doxographical (grub mtha’) and Chan Buddhist documents from Dunhuang. This study mainly puts forward the following two new viewpoints: 1) The SEPMS essentially borrows from the theories of Satyadvaya (bDen pa gnyis) and Triyāna (Theg pa gsum) as its core concepts as well as the thought of Sautrāntika-Madhyamaka (mDo sde spyod pa’i dbu ma) as its ultimate purport, almost entirely comprising the doctrine of the exoteric Mahāyāna which had been officially recognized by the Tibetan court. 2) Based on the doxography of the “Three Schools of Mahāyāna” (“Dasheng san zong”) disseminated from the Chinese scholar Tankuang (ca. 8th century) to the Tibetan translator sNa nam Ye shes sde, the editors of the SEPMS conceived Sautrāntika-Madhyamaka, a product of the close interaction between Tibetan and Chinese Buddhism during the period of the Tibetan Empire. The conception and development of the view of Madhyamaka (dBu ma), especially Sautrāntika-Madhyamaka, was a basic characteristic of the exoteric Mahāyāna during the Early Propagation (sNga dar) and onset of the Later Propagation (Phyi dar) of Tibetan Buddhism. The promulgation and influence of the SEPMS thus reflects the external constraining forces and an internal consciousness of the development of the exoteric Mahāyāna in the Tibetan Empire, as well as the historical continuity and doctrinal uniformity of the traditions of Madhyamaka in early Tibet (8th–11th centuries).