Baal HaSulam, “A Speech for the Completion of The Zohar“: Rather, we understand Dvekut as equivalence of form between two spiritual objects, and we understand separation as disparity of form between two spiritual objects.
Question: What is “equivalence of form?”
Answer: There are two categories: internal and external. For example, I see different statues. One is made of marble, another of plaster, a third one of clay, and yet another of granite, plastic, and so on. They all have the same external form, but the material is different.
In the same way, we also are required to reach an equivalence of form. First, your material—which means who you are and what you are—is revealed in the form of cotton, wool or clay, and from this material, you sculpt an upper image. Your “material” is your attributes—your desires, thoughts, everything that you are internally.
Then, you create the image of the upper from a harder material, and, although it is less pliable, you can create more accurate forms. Each time, the material gets increasingly harder, until you reach the hardest material, and, accordingly, you reach a much more accurate resemblance to the upper. It will be total accuracy, a complete equivalence of form, adhesion.
From the 4th part of the Daily Kabbalah Lesson 1/30/13, Writings of Baal HaSulam