gui-wei day pillar

未 is earth and earth controls water, so 癸 sits above its own controller. The word Tomb attaches to this pair by a roundabout path. 五行大義 calls 未 the grave of a different element, 未是木墓, and puts the grave of water at 辰, while the backward count for 癸 is what delivers Tomb to 未.

己, 丁 and 乙 are the usual residents of 未, and from 癸 they are Seven Killings, Indirect Wealth and Eating God. 三命通會 replaces 乙 with 甲 and describes 未 as the store of 甲 wood. Yang 甲 would change that last position to Hurting Officer.

In 三命通會 卷一 this is the lower half of the willow: 杨柳根, its root, with 喜冬及水，亦宜春, pleased by winter and water and also suited to spring. 壬午 had the trunk, so the book splits one 納音 between what is above ground and what is below.