My Answer: First, the Upper spiritual Partzuf descends to the lower one. The Upper One attaches itself to the lower one and assumes its form and qualities. Then, the Light comes, and, thanks to the bond formed between the Upper One and the lower one, as the Upper One ascends, the lower one is elevated together with Him.
It follows that the descent and the breaking provide the opportunity for the subsequent correction. First, the Upper One descends to the lower one, becomes corrupted, and thereby, equalizes with the lower one becoming one whole. Then when the Light comes, which is part of the Upper One that had fallen into the lower one, the Upper One can awaken because it is His Light which is the Light of bestowal.
The lower one cannot awaken from this Light because it is entirely uninspired by tales of love and bestowal. It carries only the desire for pleasure. However, thanks to their bond, as the Upper One ascends, He drags the lower one up with Him for they were in descent together. This is the miracle of correction.
From the 1st part of the Daily Kabbalah Lesson 7/5/10, Rabash’s Article “Go Forth From Your Country”