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.
There is hope for all. None can die; none can be degraded forever. Life is but a playground, however gross the play may be. However we may receive blows, and however knocked about we may be, the Atman is there and is never injured. We are that Infinite.
-Swami Vivekananda