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.
Nature, body, mind go to death, not we. We neither go nor come. The man Vivekananda is in nature, is born and dies; but the Self we see as Vivekananda is never born and never dies. It is the eternal and unchangeable Reality.
-Swami Vivekananda