The Lo Shu's deepest influence came through architecture and ritual. Read as a floor plan, the square becomes the Nine Halls, jiugong: a building of nine rooms in a three-by-three grid, each room bearing a number and its cluster of correspondences. Han sources describe the mingtang, the cosmic hall of the emperor, in exactly these terms. Moving through the halls in the order of the numbers, the Son of Heaven enacted the circulation of the year, occupying the room that answered to the season and facing the direction whose power was then ascendant, so that the state itself was kept in step with heaven by a walk through a magic square.
Cammann's study traces how the same square organised divination boards, calendrical schemes and the correlative tables through which Chinese thought bound numbers, directions, colours, elements and trigrams into one fabric. The square never retired. The flying-star schools of feng shui still work by moving the nine numbers through the nine palaces in fixed sequences, reading the shifting positions as the fortunes of a building through time, so that a modern practitioner casting a chart is manipulating the Lo Shu as surely as a Han ritualist pacing the mingtang. Nor is the square only Chinese: the same unique order-three arrangement opens the sequence of planetary kameas in Western occult tradition, where it is assigned to Saturn, and this atlas's entries on the kameas begin from the very numbers the turtle carried.