The Mandukyopanisad: With Gaudapada's Karikas and the Bhasya of Sankara ; Translated into English by Manilal N. Dvivedi

The brief Mandukya Upanishad is said to contain the essence of all the Upanishads, the teachings on the ultimate reality called brahman or atman. Its twelve paragraphs were expounded in 215 karikas, or verses, by Gaudapada, the earliest Advaita Vedanta writer. These were in turn commented on by Sankara, the founder of the Advaita Vedanta system. All three of these works are here included. This was the first time the latter two were translated. The Mandukya Upanishad is the source of the famous teaching on the four states of existence: waking, dreaming, deep sleep, and what is simply called "the fourth," a state of immersion in the absolute.