Answer: The ARI did not write anything himself. His student Marchu (Chaim Vital) wrote everything and the records were published over the course of three generations after the ARI’s death.
Baal HaSulam explained and systematized all of the Ari’s teaching. Before him, the teaching of the ARI was not arranged in an orderly fashion, and therefore it was impossible to study. That is why many people who began to study the ARI’s teaching gave it up and instead studied the works of the Ramak.
I also studied the Ramak until I discovered Baal HaSulam, and I encountered many Kabbalists who studied the Ramak instead of the ARI because everything is clear and orderly in the Ramak’s books. On the other hand, the ARI’s works were not orderly. Baal HaSulam systematized, detailed, and explained them, and gave them shape: three lines, the First and Second Restriction, the Creator and the creation, the definition of the worlds, Sefirot, Partzufim, NRNHY, KHB, ZON, he created a compilation of graphs of the Upper Worlds – The Book of HaElan.
Even though certain parts are missing which he could have put in order as well (such as Adam HaRishon and the impure worlds of BYA), apparently he did not want to work on this. Without Baal HaSulam, we would not have the teaching of the ARI and it would be impossible to understand the ARI.
When you read other Kabbalists now, you understand them because you are familiar with the works of Baal HaSulam. Without him, you would get confused. No matter what texts you look at, whether books on Hassidut, the Ramak, Agra, or others, you will only be able to understand them because you studied Baal HaSulam.
In addition, without the Rabash’s articles we would not be able to understand what is required of us and what the work of the Creator is. Without these two Kabbalists, Baal HaSulam and Rabash, who supplement one another, we would not have the right approach to the method of correction.
From the 4th part of the Daily Kabbalah Lesson 8/8/10, “Introduction to the Book, Panim Meirot uMasbirot”