The corrections take place due to the Light that comes from the teacher. The corruptions come from the environment, from the group. But only if a person tries to be incorporated in the environment, taking part in its life and work, studying and being dedicated to the cause, is he sent corrupt desires.
These special corruptions are not only foolish pride or other primitive desires, but corruptions that can draw the Light of correction upon them. This means that a person has to have defects that are totally opposite from the corrected form. He receives all these desires from the environment.
We are speaking about a person who tries to do everything that he can in order to advance spiritually. Then he receives “red light” (redness) from the group, like from a mother’s womb. The group is a mother for him. He receives the “white light” (whiteness) from the father, from the teacher, and this whiteness is his Sefirot, his attributes.
Now a person already has two lines and he has to work in the “middle line.” It isn’t that he can receive it automatically without doing anything. A person has to make efforts in order to be incorporated in this kind of work. Then to the extent that he annuls himself before the group, the teacher, the study, and the Creator, all these factors begin to operate on him and he attains a new level.
From the 1st part of the Daily Kabbalah Lesson 12/12/12, Writings of Baal HaSulam