It is closely connected with popular religious conceptions. The human body, according to Chinese medical conceptions, has nine parts, corresponding to nine celestial regions, and symbolized by Ming Tang scheme. Tai-yi star revolves around Wei star, and visits all nine regions by turn. Tai-yi deity animates the star, and it has a bodily counterpart, visiting all nine parts of body. Supposedly, any therapy for each part is prohibited while the deity resides in it.
Every table has nine columns, corresponding to nine body regions, and five rows.
Special symbolical reordering of the tables allows us to state that this pseudo-rational system has a numerological basis.