If the Light comes from above and gives its power to the lower part (AHP) of the upper level that is under the 2nd restriction (Tzimtzum Bet) to return to the 1st restriction (Tzimtzum Aleph), it begins to operate. Then this Light also enters the upper part (GE) of the lower level and corrects it. It turns out that AHP of the upper adheres to GE of the lower and they become one whole.
Absorption is when every part enters the other, like two pieces of metal that enter each other or two liquids that mix. There are different types of connection as each part gives to the other and receives from it and thus they create something new. Without it there is no life!
In fact it is very difficult and complicated to understand because this is actually the essence of life. Each part enters the other and annuls itself. It is at the point that one annuls itself that it can feel the other, perceive and receive it. It looks for the place where the other has annulled itself in order to penetrate it. This is a mutual, deep, inner penetration which is very complex and as a result each side complements itself: one by GE and the other by AHP.
Thus the upper and the lower levels acquire a new common Partzuf. Two created beings can create a third common Partzuf between them.
From the 3rd part of the Daily Kabbalah Lesson 9/08/13, Talmud Eser Sefirot