The Sand?kai (Chinese: ; pinyin: ) is a poem by the eighth Chinese Zen ancestor Shitou Xiqian (Sekito Kisen, 700-790) and a fundamental text of the S?t? school of Zen, chanted daily in temples throughout the world.
The poem's title, "", is pronounced Sand?kai in Japanese or C?ntóngqì in Mandarin Chinese. The characters, in particular the first, ? (san or c?n), can have several quite different meanings, and therefore the poem's title is susceptible to a variety of interpretations and translations.
English translations of the title, some more and some less literal, include "Merging of Difference and Unity", "Merging of Difference and Equality", "Agreement of Difference and Unity", "Harmony of Difference and Sameness", "Harmonious Song of Difference and Sameness", "Identity of Relative and Absolute", "Harmony of Relative and Absolute", "Harmony of Difference and Equality", and "Ode on Identity".
The title of the Sand?kai is the same as that of a 2nd-century Taoist text on alchemy, which is also known as the Cantong qi; in reference to the Taoist work, "" is often translated as "the Kinship of the Three".
Toward the end of his life Shunryu Suzuki Roshi gave a series of lectures on the Sandokai. These have been published as the book Branching Streams Flow in the Darkness.