Samadhiraja Sutra

The Samādhirāja Sūtra (King of Samādhis Sūtra) or Candrapradīpa Sūtra (Moonlamp Sūtra) is a Buddhist Mahayana sutra. Some scholars have dated its redaction from the 2nd or 3rd century CE to the 6th century (the date of the earliest manuscript found), but others argue that its date just cannot be determined. The Samādhirāja is a very important source for the Madhyamaka school and it is cited by numerous Indian authors like Chandrakirti, Shantideva and later Buddhist authors. According to Alex Wayman, the Samādhirāja is "perhaps the most important scriptural source for the Madhyamika." The Samādhirāja is also widely cited in Tantric Buddhist sources, which promote its recitation for ritual purposes. A commentary to the sutra, the Kīrtimala (Tibetan: grags pa'i phreng ba), was composed by the Indian Manjushrikirti and this survives in Tibetan.

The text is commonly known as the King of Samadhis Sutra (Samādhirājasūtra, Tib. ting nge 'dzin gyi rgyal po'i mdo), and it is also known as the Moon Lamp Sutra (Skt. Candrapradīpa Sutra, Tib. zla ba sgron me’i mdo) after the main bodhisattva in this sutra.

The full Tibetan title in the Kanjur is:

The Chinese have preferred Yueh-teng san-mei ching, corresponding to *Candrapradīpa-samādhisūtra (Moon Lamp Samadhi Sutra).

Peter Alan Roberts writes that "it is impossible to be sure when this work first appeared in writing; indeed, the sūtra is very likely a compilation of earlier shorter works. None of the complete extant Sanskrit manuscripts can be dated to earlier than the sixth century." However, he also notes that it is cited in the Sūtrasamuccaya (c. 4th century or later) and also may have been referenced to by Asanga (4th century). Gomez and Silk write that "an educated guess is that the text took form between the second century C.E., when it is generally believed Madhyamaka thought emerged as a distinct philosophical tradition, and the sixth century, the date of the Gilgit manuscript, the earliest extant recension of the text. This does not mean that the text was not in existence in some form before the second century." They also note that a Chinese translation of the text by An Shigao (fl. mid-second century CE) is recorded in Chinese sutra catalogues.

Andrew Skilton writes that this large sutra is probably a composite work which "bears certain affinities with the Prajñāpāramitā literature and other early Mahayana scriptures". He also writes that there were various recensions and versions of this sutra in circulation in India.

According to Roberts, "at least two shorter independent works that may have existed earlier appear to have been incorporated into the King of Samadhis Sutra." These are:

The King of Samadhis was translated into Chinese by Narendrayaśas (517–589), an Indian monk from Orissa, who titled it The Sūtra of the Samādhi of the Lamp of the Moon (月燈三昧經, Taishō 639). Two other Chinese translations include an alternative version of the equivalent of the sixth fascicle by Xiangong (逮慧三昧經, The Attainment of Wisdom Samādhi Sūtra) and an alternative translation of the equivalent of the seventh fascicle by Xiangong (文殊師利菩薩十事行經, The Ten Practices of Mañjuśrī Bodhisattva Sūtra).