These combinations seem to accord with common sense, for instance wood "rules" the direction East because growing trees like the sunlight and the sun rises in the east. Metal similarly "rules" the West since metal is by nature cold and dead, and the west is the direction of the setting sun and the lack of light which spells etiolation for plant life.
這種連結似乎也滿合乎常理，例如木所「主」的方位在東，因為樹木生長，喜歡陽光，而東方正是太陽昇起之處；同樣的，金的稟性清涼肅殺，而西方正是太陽下山、草木不生的地方，因此金和西方便被結合在一起。