The Zohar, Introduction, Article “Lock and Key,” Item 44: Within those gates there is one lock and one narrow place, in which to insert that key.
First of all we must find the key and the lock. What are they? Where are they? And how can we make them match one another? Inserting the “key in the lock” means establishing a connection between opposites by attaining equivalence of form.
And finally, how can we open the lock? How do we turn the key in it? Do we “turn” ourselves in the upper one in order to become similar to Him? Or is all of this none of our own acts, but only His? Should we just evoke or initiate them?
These are questions that a person discerns all the time. The lock and key represent a protective mechanism that adapts us to the system of the world of Atzilut, to Arich Anpin.
He divided himself into two parts: upper and lower. The upper part is concealed while the lower part becomes revealed to the lower ones. We do not have a direct connection with Him and thus we turn to Bina, who came to the outside, becoming a conductor of the upper governance.
The Zohar has a lot to say about this because we have to awaken Lights upon us that will project inside us the mechanism that corresponds to the lower part of Arich Anpin. Our task is to give the upper one an opportunity, again and again, to work on us and give us forms that are increasingly more perfect. At the end we must take on the laws of the system that is connected to us, lower ourselves before it, and become similar to it.
From the 1st part of the Daily Kabbalah Lesson 12/21/10, The Zohar