This Upanishad belongs to the Atharva Veda. As the name of the Upanishad suggests, the teachings revealed in it are such as to leave its students clean, like a shaven head (mundaka), rid of the veil of ignorance. The lucid translation of the text along with Shankaracharya's commentary on it is an additional aid to comprehend the profundity of the subject.
Be not afraid, for all great power throughout the history of humanity has been with the people. From out of their ranks have come all the greatest geniuses of the world, and history can only repeat itself. Be not afraid of anything. You will do marvelous work.
-Swami Vivekananda