He is the ruler of the seven firmaments. The Righteous-One (Yesod) is the firmament, which separates between the waters, between the higher sea which is Higher Mother (Binah), and the lower sea which is Lower Mother (Malkhut).
And about that it is stated:cliv ‘There is nothing between the higher waters and the lower waters, except a hair’s breadth’, as the Masters of the Mishnah have established. And this hair-strand is the Righteous-One. And not for nothing did the earlier-sages establish:clv ‘The blessed Holy One is exacting with the righteous, even as a thread of hair’.