Hetu & Luoshu

From the Yellow River came the Diagram, from the Luo River came the Script, and the Sages patterned themselves upon them. These are the foundational charts and prophecies of the study of the Yi, holding within them, it is said, the very numbers of Heaven and Earth. In former times they were found chiefly among the apocryphal texts appended to the classics in the Book of Sui: Treatise on Classics, serving to supplement the classics. Scholars have long noted that their origins are so remote, making their authenticity difficult to determine. Yet as "the wellspring of the Great Yi and the source of all diagrams and writings," there has not been, in a thousand years, a single scholar of symbols and numbers who has not traced his learning back to them.