Part 3: The Line shines within the inner essence of each Sefirah as the soul of the souls... The shining of the Line within the inner essence corresponds to the concept of the “irrigation of the Tree” mentioned in various places in the Zohar (see Tikkuney Zohar, Second Introduction, 17, 1). The “irrigation of the Tree” is not the same as the mental powers, for these vary according to the individual structure of each Partzuf, as explained in the writings of the ARI.
Part 4:...and in this aspect it is completely equal on all levels. This is necessarily the case, as it states in the Zohar (Ki Tetze 281a): “He does not change in any place”. This fact is obvious, for the Line constitutes the perfect action of Eyn Sof, blessed be He, in executing all the bounded laws of the Residue, as explained earlier (Opening 25). We may discern the same perfection in Keter, the highest of all the laws and Sefirot, just as in Malchut, which is the last. For everything that Eyn Sof does, small or great, He does to perfection. If so, the Line is the same on all levels. It is indeed fitting that Eyn Sof does not change at all, and that only the Sefirot change. This is because the Sefirot shine according to the readiness of the created realms and beings to receive. Since there are differences between the degree of readiness of different receivers, there are differences between the Sefirot. However, the Line of Eyn Sof shines in accordance with His perfection, and change is not applicable on this level.