The mansion of Brahman is open to you, I think, on nachiketa. Take the red pill, fearlessly walk through these doors. But yes, it's irreversible. Once you see, you cannot unsee. Once you walk through, you cannot take it back anymore. That's why sometimes I say, don't be in a hurry to become enlightened. You cannot undo this.
Swami Sarvapriyananda teaches the Katha Upanishad, which is one of India's most revered texts and a part of the Vedas. It is a collection of philosophical poems representing a conversation between the sage Naciketas and Yama (god of death). They discuss the nature of Atman, Brahman and Moksha(liberation).