The Zohar, Chapter "VeYechi (And Jacob lived)," Item 442: At the end of correction, when the whole of Malchut is corrected, the Zivug of GAR de GAR will return, meaning that [the Creator will enter] Jerusalem above, and this explains, “I have sworn to David My servant,” the oath that the Creator will not enter Jerusalem above until Israel enter Jerusalem below.
This is talking about the correction in three lines. We receive two lines or forces from Above. But the ability to cut off the left line and attract the right line, and then to combine the right and left lines the right way in the middle line – all of this happens only through the model or formula that we reveal between us.
I don’t know what the middle line is. No one brings it to me ready-made and it does not come to me from Above because otherwise I wouldn’t have a place in which to recreate myself, to conduct my search, to make efforts, and to make revelations on the path.
The middle line is very unclear. You were given two forces and they are at your disposal. However, you can destroy the world using either one. How then do we reach the state where we find the right combination of two lines – in the screen de Hirik, from below upwards? How do we even start to connect these two opposite lines?
This is the work done between the souls because it can be actualized only in the connection between them. The right and left lines exist in the form of natural forces, while the middle line can only be created in the connection between the souls.
This can be called "group psychology." Here, through the search between us, we have to find how to create the eternal state, the right combination of these two lines through the connection between us.
The way to check our work is by revealing the right intention between us, "for the sake of the Creator." Then revelation takes place, we attain the middle line, and acquire the opportunity to use these two lines correctly.
From the 2nd part of the Daily Kabbalah Lesson 9/27/10, The Zohar