The root of the creations is in the seven lower Sefirot, while the first three only direct them. When the vessels broke, the first three Sefirot did not break.
The first three Sefirot (Keter, Chochmah, Binah) did not break the way the seven lower did. The asymmetry has consequences for the entire repair-architecture.
The Nekudim unit (Op. 36–50) treated the breaking as if it concerned all ten Sefirot equally. Op. 51 reveals that this is not quite right. The first three did not break; the seven lower did. The chapter introduces the States of the First Three Sefirot unit (Op. 51–53) and the structurally crucial mochin de-katnut / mochin de-gadlut spectrum.
The root of created beings — the structural source of all that emerges as cosmos — is the seven lower Sefirot: Chesed, Gevurah, Tiferet, Netzach, Hod, Yesod, Malchut. These are the constructive Sefirot (binyan); they are what builds the cosmic structure. The first three (Keter, Chochmah, Binah) do not build directly; they are crowns over the lower seven, directing them.
When the breaking happened, the Vessel's failure occurred at the level of the constructive Sefirot. The first three were driven away — the link between them and the lower seven was disrupted — but the first three themselves remained intact. Their back-parts (achorayim) of NHY (the lower three of the first three's downward-radiation) were flawed, but the first three's main structure was not broken.
This introduces mochin de-katnut (small mind) and mochin de-gadlut (great mind) as the cosmological spectrum across which the first three's relation to the lower seven varies. In katnut, the link is minimal — the first three are present but their direction reaches the lower seven only at small scale. In gadlut, the link is full — the first three direct the lower seven at full operational scale. The cosmic government's middle phase oscillates between these states, and the closing chapters' rhythm of First/Second Maturity (Op. 128) operates on the same spectrum.