The Mundaka Upanishad is the Mantra Upanishad. It has three chapters and each chapter is divided into subchapters called 'Khanda'. The Mundaka Upanishad has sixty-four Mantras in total.
It is described at the beginning of Mundaka Upanishad that it was first told by Brahma to his son Atharva. Atharva passed the knowledge to Satyavaha, Satyavaha taught it to Angiras, who finally passed it to Shaunaka. The Mundaka Upanishad is in the form of dialogue between the teller and the listener.
The knowledge of Mundaka Upanishad is divided into two categories. The knowledge of Self Realization is called Para Vidya or Divine Knowledge. The knowledge other than Para Vidya is called Apara Vidya or Knowledge of Material World. The Mundaka Upanishad elaborates the greatness of Para Vidya. This Upanishad is the first text that mentions the six disciplines of Vedanga.
The word 'Mundaka' means 'one with a shaven head', which is a feature of monkhood. This metaphorically means one who has been shorn of his ignorance. The Mundaka Upanishad presents its teachings maintaining a logical sequence. It says that just as spiders create the web from their own excretion and finally consumes it by themselves, Universe also manifests from Brahman and finally return to Brahman. The Brahman is the ultimate reality and individual soul emerges from and merges back to the universal soul. Mundaka Upanishad sets excellent analogies to represent the relationship between Brahaman and individual. It winds its answers with the highest philosophical thoughts and to the answers of philosophical questions it postulates that both efficient cause and material cause originates from the same Ultimate reality.
The Mundaka Upanishad revealed that the correct aim of prescribed rituals is to prepare an individual to lead a disciplined and selfless life. But this is only the preparatory stage of attainment of real purpose of life, which is feeling oneness with the highest objective, the Brahman or the Ultimate Reality. At the stage of achievement of this ultimate merging with great Brahman, one becomes free from space, time, 'Nama' (name) or 'Rupa' (form). The unison with the ultimate reality is just like the merging of rivers with the ocean.
The Mundaka Upanishad is mostly remembered as the source of the phrase 'Satyameva Jayate', the national motto of India, written below the National Emblem having four lions.