Question: What is the law of the system of Arvut (mutual guarantee)?
Answer: The law of this system is absolute reciprocity. This is how it is described in the Torah: “As one man with one heart.” This means that the one desire in the entire system, mutual bestowal, is realized in the adhesion with the Creator. The law is defined by the word “one,” as in “unity.”
It could be said that unity of “one” cannot be a law. But the definition of “one” contains many different properties connected with each other above hatred and rejection by relations of love and bestowal. This is the internal formula of the system: Qualities opposite in their nature are connected above this opposition by the law of equivalence of form.
This is the way our body and any integrated system are constructed. In order for such a system to exist, it must be built from the different forms and opposite parts over which there operates a universal law: existence for the sake of one unified purpose.
From the Daily Kabbalah Lesson 10/15/10, "The Arvut"