The Oral Torah, – where the Lower Shekhinah is – is called ‘mouth’ from the aspect of the Righteous-One. Because thus does the word peh (mouth, =85), add up to the numeric-value of the word milah (word) (circumcision, =85), which is ‘every mouth’.
And because of this: And by the hand of every man he seals... (Job 37:7) And She (Malkhut) is to the left, for Higher Mother is there, of whom it is stated: ‘sign us for life!’ And the Righteous-One (Yesod), because of Her, is called, ‘the book of life’,
as we say:xcivLiturgical: High Holidays ‘And in the book of life... etc.’