Yibu zonglun lun 異部宗輪論

Yibu zonglun lun 異部宗輪論 "Treatise on the cycle of the formation of the schismatic doctrines" is a Buddhist scholastic work belonging to the Sarvāstivāda School (Ch. Shuo yiqie you bu 說一切有部). The term "different schools" (yibu 異部) refers to various non-orthodox Buddhist divisions, while "wheel of doctrines" (zonglun 宗輪) signifies that the doctrines upheld by these schools accept and reject each other in turn, revolving like a wheel without fixed stability.

The work, in the Sanskrit original called Samayabhedoparacana-cakra, records the history of the divisions within Indian Buddhism after the Buddha's passing and describes their respective doctrines. It was composed by the ancient Sarvāstivāda master Vasumitra (Ch. Shiyou 世友, 2nd cent. CE) and translated into Chinese during the Tang period 唐 (618-907) by Xuanzang 玄奘 (602-664). The text consists of one juan. There are two alternative translations, namely the anonymous Shiba bu lun 十八部論 (T2032, also called Fenbie lun 分別部論), and Paramārtha's (Ch. Zhendi 真諦, 499-569) Bu zhi yi lun 部執異論 (T2033, also titled Bu yi zhi lun 部異執論).

The treatise is divided into two major sections, prefatory gāthās (Xu fen ji song 序分偈頌), and the main prose exposition. The introductory verses mainly explain the circumstances that led to the composition of the treatise and provide a brief account of the author's life. The main body of the text explains the reasons and timing behind the split of Buddhism into different schools. It recounts the controversies that arose over the "Five Points of Mahādeva" (Datian wu shi 大天五事). Mahādeva argued that even an arhat (Chinese transcription aluohan 阿羅漢, one who has attained the highest spiritual realisation through practice) still has five limitations—physically, mentally, and spiritually. To be an arhat is therefore not the ultimate spiritual state; only the Buddha signifies the ultimate attainment. The disputes caused by this doctrine led to the division of the originally unified Buddhist community into two main groups, the Mahāsāṃghika (Ch. Dazhong bu 大眾部) and the Sthavira (Shangzuo bu 上座部) traditions. In the end, these two further split into eighteen different schools of the Hīnayāna (Theravada) tradition.

The book also explains doctrinal positions held by various Buddhist schools on several important theoretical issues, categorising them into eleven groups. Among these are questions such as whether all speech of the Tathāgata (Ch. Rulai 如來, i.e., the Buddha) constitutes the turning of the Wheel of Dharma (zhuan falun 轉法輪); whether bodhisattvas (Ct. Pusa 菩薩) still possess defilements like greed or anger; whether an arhat can fall back from that state; and whether the three ages (past, present, and future) exist as real entities or only as nominal or conventional existences.

The Yibu zonglun lun is regarded as an important source for studying the origin, development, and doctrines of the early Buddhist sectarian schools.

The most significant commentaries were Guiji’s 窺基 (632-682) Yibu zonglun lun shuji 異部宗輪論述記 and Paramartha's commentary. Both are lost.

There is also an English translation by Masuda Jiryō 增田慈良. 1925. Origin and Doctrines of Early Indian Buddhist Schools: A Translation of the Hsüan-chwang Version of Vasumitra's Treatise. Leipzig: Verlag der Asia Major.