Hétú*Luòshū: 河圖*洛書 Chart of the [Yellow] River and Writ of the Luo [River]
The author of this entry, Isabelle Robinet begins: “According to legend, the Hetu emerged from the Yellow River on the back of a “dragon-horse” (lóngmă 龍馬) during the reign of the legendary emperor Fú Xī 伏羲. Similarly, the Luoshu came out of the Luo River on the back of a turtle”.
The first reference to Luoshu was made in the text created probably in the second century CE, in the fifth century it was related ‘to a liturgical cult of sexual union practiced by the school of the Celestial Masters (Tianshi dao) and for us, humble readers of Encyclopedia of Taoism it will be enough to know how to place the numbers 1 to 9 in the table in the way that the sum of the numbers in vertical, horizontal, and diagonal directions will be always 15. I can imagine the fullness of joy of the person who did it the first time. The joy must be (and is) truly awesome to the present days!
4 9 2
3 5 7
8 1 6
In the the Hetu case a magic square arranges the numbers such way that they form a cross, or three concentric squares:
8 3 5 4 9
Numbers 1-5 are called ‘generative’ (shēng 生) and numbers 1-9 are ‘performative’ (chéng 成), they don’t serve rituals recently but neidan alchemists earlier used them making ‘Three Fives’ (sānwŭ) important in the process of alchemical mystery.
If someone wants 214 pages of details about Luoshu, probably a book Legacy of the Luoshu by Frank J. Swetz can be helpful. This is about the 4,000 year search for the meaning of the magic square of order three (of course, fēngshuǐ 風水 is discussed too), contains many pictures and documents, takes you for a short time to Babylonia, Greece, Egypt, India, Tibet, Japan, and the Islamic World. It is written by a mathematician and an educator, hence the style is cool, literally 🙂