These two ideas – that the Sefirot shine according to the readiness of the receivers, while the Line is like the soul in the body – are implicit in the Zohar. “The Master of the Universe deals with all the different creatures in each generation according to their deeds – just as the soul acts in accordance with each individual limb. Depending on the limb with which a man performs a mitzvah, the soul is said to have the corresponding attribute….” (Zohar, Pinchas 256b).
A third distinction that must be made in this connection is between the root of the rule of unity (יחוד, yichud) and that of the rule of reward and punishment, which I have already discussed. The root of the rule of reward and punishment lies in the Sefirot, and since the rule of reward and punishment is responsive to men’s deeds, the Sefirot change accordingly. However, the rule of unity goes towards a single goal in every action with no change at all. This is the Line, which is equal on all levels. You must understand that the equality of the Line on all levels is absolute. For sometimes two things may be of equal value, or they may be equal in a certain aspect by virtue of which they are in the same position or come under one category. In some cases they may be completely equal. However, the equality of the Line is absolute on all levels, and this should be obvious from all the proofs we have adduced, because the action of the Line is literally equal on every level without any change at all.