The Upanishads are essentially presented for the continued spiritual progress of the individual. If the Vedas emphasize and primarily consist of worship to the demigods for material needs and only hint at the prospect of spiritual liberation, then the Upanishads start to explain how worldly attachments need to be renounced so we can surrender to God. The word Upanishad literally means to sit down (shad) near (upa) and below or at the feet with determination (ni). So it indicates that the student should sit near the feet of one’s spiritual teacher and listen with determination to the teachings. Only through such absorption can one learn how to apply the teachings in practice. Sitting at the feet of the teacher is both a sign of respect and humility, but also exhibits a natural flow, like water, from something high to that which is lower. Thus the student becomes a natural receptacle for such knowledge.

Another meaning of the word (shad) in Upanishad means to destroy. So the spiritual knowledge the student receives from the teacher destroys the ignorance of the true nature of the world and his own self. As one’s ignorance is destroyed, enlightenment can follow.

The Upanishads are a collection of 108 philosophical dissertations. The Muktikopanishad (verses 30-39) lists all 108. However, there are over 100 additional compilations if you also count the lesser Upanishads that are not actually part of the primary group, making a total of well over 200. Out of all the Upanishads, the following eleven are considered to be the topmost: Isa, Kena, Katha, Prasna, Mundaka, Mandukya, Taittiriya, Aitareya, Chandogya, Brihadaranyaka, and Svetasvatara.

The Upanishads were considered the secret and confidential knowledge of reality. They mainly focus on establishing the Absolute as nonmaterial and describe it as Brahman: the eternal, unmanifest reality, source and ultimate shelter of everything. The Brahman is said to be incomprehensible because it is without material qualities or form. The secret to understanding Brahman according to the Upanishads is that they describe the Absolute as having no material qualities or material personality, but consists of spiritual qualities.