Answer: According to Kabbalah, a secret is something that we have not yet discovered. As a rule, we disclose any object, any phenomenon in four aspects of immersion into it. That is, we continuously attain the four stages of its development.
If we begin to perceive an object or a phenomenon in the first stage but see that there still other aspects, then our state is called sensing the mystery.
From the Kabbalah Lesson in Russian 1/22/17