Why did Kabbalists choose “the language of branches” to explain their thoughts to others? Let’s assume that I understood the connection between the root and branch on its very first level, while someone else managed to understand it at a higher level, and another person understood it at an even higher level. In any case, a branch will always remain a branch.
A child knows that if he plugs a cord into an electrical outlet, then his toy will start working. I know that there is electricity in the plug and that it comes to my house through wires. A person who is more technically advanced knows that there is a power station providing the electricity, and so on. We’re all talking about the same process, regardless of how well each of us understands the details or how deeply we see “the root.” Roots continue in the direction of their highest source, but a branch in our world remains a branch.
“The language of branches” originates from reality itself. Therefore, we don’t need to invent another language to express spiritual notions; it simply cannot be done. This language was created for us by Nature to be used for communication between us and with the Creator. In his book, The Torah, Moses was the first to use this language to describe the path of spiritual attainment at all levels.
The Book of Zohar explains Moses’s commentaries and adds its own language. It was written by Rabbi Shimon, who went through the same steps as Moses did, which are the same steps that each person will have to go through. His description of those steps provides additional explanations of the connection between a root and a branch. This is why The Book of Zohar is so useful in attracting the Surrounding Light (Ohr Makif) from the root to the branch, meaning to us.
Baal HaSulam described the connection between the root and branch in even more detail by adding Kabbalistic definitions and explanations of their connection through the three lines. However, all of these authors talk about the same exact picture and its roots; each Kabbalist just adds his own description of the connection. This increases the force of the spiritual ascent provided by the book and the amount of Ohr Makif that descends upon a person reading it, thus paving the path to the Upper World for him.