Answer: There are no secrets! A secret is what a person doesn’t want to reveal because his ego repels it by saying: “Don’t go there, this is a secret.”
The wisdom of Kabbalah was never a secret. For 15 generations beginning from century zero to the 15th century it was hidden until humanity developed.
However, there are parts of Kabbalah that were always revealed and there were parts that were hidden because people would misunderstand them. Even today it is possible to open The Book of Zohar and not understand even one word. This is because in order to do that, it is necessary to have attained the state the Kabbalists describe.
From the Kabbalah Lesson in Russian 5/29/16