Upanishads are verses from the Vedas that have been compiled as independent and complete sets. Traditionally the verses in each Veda have been classified as Mantra portion or Brahmana portion. Within the Brahmana portion, a further sub-classification of verses has been done, namely Brahmana-Aranyaka-Upanishad. Upanishad means essential thought or guiding principle.

The Mandukya Upanishad is attributed to the Atharva Veda. It gives a mathematical picture of the sacred syllable OM and its relevance to the Awaking, Udreaming and Mmmsleeping states. The Turiya or Transcendental state is described as the amatra or the fourth state, i.e. always available yet rarely discernible.

This book explains the crux of the verses in easy to grasp contemporary language. Contains original verse in Sanskrit with a Latin
transliteration and an English commentary. For the Sanskrit enthusiast each verse has Padachheda and Anvaya with Vibhakti cases. Uses clear well-spaced Devanagari font.

सर्वं ह्येतद् ब्रह्मायमात्मा ब्रह्म सोऽयमात्मा चतुष्पात् ॥ २
sarvaṃ hyetad brahmāyamātmā brahma so'yamātmā catuṣpāt ॥ 2

प०) सर्वं हि एतत् ब्रह्म अयम् आत्मा ब्रह्म सः अयम् आत्मा चतुष्पात् ॥
अ०) सर्वं n1/1 हि 0 एतत् n2/1 ब्रह्म n2/1 ।
All verily this Brahman (is).
अयम् m1/1 आत्मा m1/1 ब्रह्म n2/1 । This Soul Brahman (is).
सः m1/1, अयम् m1/1 आत्मा m1/1, चतुष्पात् n2/1 ॥ (all) That, (and) This Soul, four states (has).
चतुष्पात् from stem चतुष्पद् n ॥