In Sanskrit, sutra means ‘thread’ as in a string of pearls forming one complete necklace. Sutras are thus pearls of the Buddha’ s wisdom (prajna) threaded to form a vast, cohesive body of recorded teachings known as the tripitaka, that also includes the vinaya (rules of conduct) and the abhidharma1 (analysis of reality). Many sutras are discourses that supposedly derive directly from the historical Buddha, Shakyamuni; only one, the Platform Sutra by Huineng (638-713), the sixth patriarch of Chan (Zen) Buddhism, is openly ascribed to someone other than Shakyamuni.

Most sutras begin with the phrase “Thus have I heard.” Whether historically accurate or not, the “I” refers to Ananda, one of Shakyamuni’ s principal disciples, who had the monumental task of remembering and reciting the Buddha’ s many discourses. Following this customary phrase, the time, place, and reasons for the discourse are usually stated. Then the discourse begins, sometimes before an assembly of thousands. Often the form of a sutra is a dialogue between the Buddha and his disciples, or between the Buddha and a bodhisattva. 2 The style is usually didactic and repetitive, most likely to ensure that the concepts sink into the minds of the readers.

Opening with the line “Avalokitesvara Bodhisattva, while coursing in deep prajnaparamita,” the Heart Sutra, at least in the Chinese version, departs from the usual “Thus have I heard.” The Heart Sutra also departs from the typical sutra format in other ways, and for good reason. The Heart Sutra appears to have been excerpted from the much larger Mahaprajnaparamita-sutra, the Great Sutra of Liberating Wisdom. This vast sutra of more than six hundred volumes is actually a collection of some forty smaller sutras focusing on the realization of prajna, or wisdom. Both the Diamond Sutra and the Heart Sutra are found within the Mahaprajnaparamita-sutra, which actually contains the text of the Heart Sutra in three different places.