Rabbi Shimon “cries” (tears are a symbol of a small state, Katnut), as if being unable to understand how to pass to us this enormous Light that he and his 10 disciples unveiled, in order for the souls of our time, beginning with our generation, to use it.
And then, he discovers that it can be achieved with the help of his student, Rabbi Abba. He explains that Rabbi Abba was able to reveal secrets “discretely” because he possessed a unique soul from the Surrounding Light. Hence, through him, through the Surrounding Light, we can receive all corrections.
And generally speaking, all corrections that we receive come only through The Book of Zohar, or through Rabbi Shimon and Rabbi Abba, through the Surrounding Light. And the source of all Kabbalistic books is also The Zohar since all of them were written on its basis. Without The Zohar, no Kabbalist who lived after it had been written would have been able to uncover spirituality and write a book. He wouldn’t have been able to adhere to the Light; after all, The Zohar is its source.
And when Kabbalists have reached attainment through The Zohar, they finally start writing themselves, as it happened with the Kabbalists of all generations: Ari, Rambam, Rashi, Agrah, and others. But all of them had one source. Clearly, we are not talking about those who came before Rashbi, Abraham, or Moses, who are parts of the upper system.
But we have no source of revelation other than The Zohar. Therefore, Baal HaSulam writes about how grateful we should be to such a soul as Rashbi, because without him, the Light wouldn’t reach us and we would remain cut off from the entire upper system.
From the 4th part of the Daily Kabbalah Lesson 12/14/10, Writings of Baal HaSulam