Upanishad means receiving knowledge while sitting near the teacher. These are conversations between self realized souls and their students on the subject matter of Absolute truth. The philosophical aspects of all the important processes and practices of k nowledge (known as vidyas) that are given in the Vedas are discussed in the Upanishads. Veda means knowledge and anta means end. Upanishads are known as Vedanta, end of knowledge.
In the Upanishads the description is more or less negation of the material conception of everything, up to the Supreme Lord. It is very important to note that there is no denial of the spiritual, absolute, transcendental conception in the Upanishads. The purpose of the Upanishads is to philosophically establish the personal feature of the Absolute Truth as transcendental to material names, forms, qualities and actions.
There are 108 Upanishads, as accepted by disciplic succession. Among them the following are considered as topmost:
1) Isa
2) Kena
3) katha
4) Prasna
5) Mundaka
6) Mandukya
7) Taittiriya
8) Aitareya
9) Chandogya
10) Brhad-aranyaka
11) Svetasvatara
Darshana means, sight or vision. In the Vedanta philosophy, the first question is, what is the source of everything? There are philosophers who saw different stages of the original source, and explained philosophy according to their vision. These are known as darshanas. They are also known as sad-darshanas (six systems of philosophy).
The six philosophical treatises are:
- Nyaya propounded by Gautama
- Vaisesika propounded by Kanada
- Sankhya propounded by Kapila
- Yoga propounded by Patanjali
- Purva (karma) Mimamsa propounded by Jaimini
- Uttara (brahma) Mimamsa propounded by Vyasa
Nyaya-darshana, the philosophy of logic, maintains that the atom is the cause of the cosmic manifestation.
Vaisesika-darshana, philosophy of specialised logic, maintains that the combination of atoms is the cause of the cosmic manifestation.
Sankhya-darshana, philosophy of analytical study, maintains that the material nature is the cause of the cosmic manifestation.
Yoga-darshana, philosophy of mystic perfections, maintains that universal consciousness is the cause of the cosmic manifestation.
Purva (karma) mimamsa-darshana, philosophy of actions and reactions, maintains that fruitive activities are the cause of the cosmic manifestation.
Uttara (brahma) mimamsa-darshana has two different categories:
The impersonalists maintain that the impersonal Brahman effulgence is the cause of the cosmic manifestation.
After studying the six philosophical theses, Vyasadeva completely summarized them all in his Vedanta-sutra darshana: The Absolute Truth is the Supreme Personality of Godhead, who is the cause of all causes.
Anyone who wants to establish his own philosophy certainly cannot explain any scripture according to the principle of direct interpretation. Among the six kinds of philosophers up to the impersonalist brahma-mimamsa philosophers, none really cares for th e Supreme Personality of Godhead, who is the cause of all causes. They are always busy refuting the philosophical theories of others and establishing their own.
Nyaya and Vaisesika philosophers by accepting atoms as source have rejected the Supreme Personality of Godhead.
The Sankhya philosophers do not accept the Supreme Personality of Godhead, because after scrutinizingly analyzing the material elements, they have come to the conclusion that material nature is the cause of everything.
The Yoga philosophers imagine a form of the Absolute Truth within many forms , and thus do not give any information about the transcendental Personality of Godhead.
Purva (karma) mimamsa philosophers maintain that if there is a God, He is subjected to our fruitive activities. Therefore they do not see any need to become devotees of the Supreme Personality of Godhead.
The impersonalist Uttara (brahma) mimamsa philosophers say that everything is an illusion. Headed by philosophers like Astavakra, they stress the impersonal Brahman effulgence as the cause of everything, rejecting the transcendental Personality of Godhead, who is also the source of that Brahman effulgence.
Srila Vyasadeva wrote the Vedanta-sutras and taking the essence of all vedic literature, established the supremacy of the Supreme Personality of Godhead.