Interrelation of Zeir Anpin and Nukva in the developmental chain and the governmental order.
Daat distributes 5/5 — evenly between Z"A and Nukva. The parallel partnership: man's service elicits God's influence.
Op. 125 specifies Daat's distribution and the operational form of Z"A-Nukva interrelation. The 5/5 distribution is structurally important; the parallel-partnership doctrine is the operational form.
Daat distributes 5/5 — five aspects to Z"A, five to Nukva — because Daat is the balance-attribute. It stands between the right column (Chesed, Kindness) and the left column (Gevurah, Judgment), partaking of both, and is therefore the natural distributor for symmetrical operations.
The operational form: Z"A and Nukva in parallel partnership. Both partners are operational; both contribute; their coupling produces the cosmic-operational effect.
Man's service elicits God's influence. The parallel partnership requires human service as the operational input. When humans serve, the cosmic-operational flow becomes available; without service, the flow is constrained.
This grounds the deed-dependent operating mode of the closing chapters. Op. 138's eight-stage Coupling order operates because of the Op. 125 framework: man serves; Nukva receives the service-input; Z"A turns toward Nukva to send the cosmic-operational response; the response flows down to the lower creations.
Op. 126 (spread of Daat through the body — the operational mechanism). Op. 138 (the closing eight-stage operational completion).