Rabbi Akiva was Rashbi’s (Rabbi Shimon) teacher, and naturally knew everything that would be written in The Book of Zohar. He knew even more than Rabbi Shimon, but he could not reveal it. In order to reveal this knowledge, Rabbi Shimon united with ten other people and created a system reflecting the state of final correction. Therefore he was able to give an explanation in a form that previously nobody was able to articulate.
He adapted Kabbalah to the “last generation” that we live in today, which is the reason we value The Book of Zohar. Rabbi Shimon took the science of Kabbalah and clothed it into the correct Kli for final correction. Therefore, we can use the light that reaches us through his group.1
From the 1st part of the Daily Kabbalah Lesson 12/20/19, Writings of Baal HaSulam, “Introduction to the Book, Panim Meirot uMasbirot”
1 Minute 57:20