Systematic Philosophy in the Vedic Literature.
Most of the important foundational principles of the Vedānta are found in Rig Veda but they have been presented through poetry.
The Sanskrit word for a poet — Kavi also means a sage, a seer or a visionary.
The method by which the sages arrived at these views, their reasoning and the arguments put forth in support of them, are not found in the Veda Samhitas themselves.
Thus there is no systematic philosophical methodology to be found in the Samhita portion of the Vedas. All attempts at a systematic philosophical investigation are to be found in the sections of the Vedas known as the Upaniṣads, where questions about ātman, Brahman and the cosmos are raised and discussed at length.
Some of the Upaniṣads are written in verse and they follow the pattern of the hymns of the Rig Veda, while others, though written in prose, also lack the support of cogent philosophical reasoning. Some of them are in the form of dialogues where propositions are presented and supported by arguments.
Existential Problems of the Upaniṣads
· Who are we? What is Self (ātman)?
· What is the Supreme Reality (Brahman)?
· What is the Source from which all things originate, by which all live and into which all dissolve?
· What is that by knowing which everything can be known?
· What is that by knowing which the unknown becomes known?
· What is that by knowing which one can be liberated from sorrow (duḥkha) and attain immortality?
These questions in themselves are indicative of the fundamental belief of the Indian scholars that there is an all-pervasive Reality underlying all things; from which they arise, in which they exist and into which they ultimately all return. And that there is some Reality by knowing which immortality or cessation of suffering can be attained.
The All Pervasive Brahman/ ātman
The Ultimate Reality postulated is sometimes called Brahman (The Immensity), sometimes ātman (The Life force) and sometimes simply Sat (Being).
The mahāvākyas or great utterances of the Upaniṣadic sages are the foundation of the super-structure of Vedānta.
Ātmā vā idam eka evāgra āsīt — at first, there was ātman alone (Aitareya Up. 1.1 & Bṛhad Up. 1.4.1)
Ātmaivedam sarvam iti — all this is ātman (Chāṇḍogya 7.25.2)
Ātmani khalv are vijñāte idam sarvam viditam — once the ātman is known everything is known. (Bṛhad Up. 4.5.6)
Sad eva saumya idam agra āsīd ekam advitīyam. — Then, being (Sat) alone was there at the beginning and it was one without a second. (Chand. 6.2.1).
Sarvam khalv idam brahma — all this is Brahman. (Muṇḍaka 2.2.11 & Chand. 3.14.1)
Idam ātma brahma — this ātman is the Brahman (Brhad, 2.5.11)
Aham brahmāsmi — I am Brahman (Brhad. 1.4.10)
Brahma vā idam agra āsīt — Brahman indeed was this in the beginning. (Brhad. 1.4.10)
Here, we see that in all these different contexts, the terms Brahman, Ātman and Sat have been used synonymously.
The term Brahman is derived from the root brh — ‘to grow, to burst forth.’ The derivation suggests gushing forth, bubbling over, ceaseless growth, brhattvam.
Sankara derives the word ‘brahman’ from the root brhati to exceed, (atiśayana) and means by it eternity, and absolute purity.
For Madhva, brahman is the Supreme Person in whom all the good qualities are located in their fullness,(brhanto hy asmin gunah.)
Rāmānuja declares that Brahman is Nārāyaṇa — the Ground of Being.
The sages of the Upaniṣads attempt to establish the reality of Brahman from an analysis of the facts of nature and the facts of inner life.
‘Who knows and who can declare what pathway leads to the gods?
Seen are their lowest dwelling-places only;
What pathway leads to the highest, most secret regions?’ RV 3:54
The Brhad-aranyaka Upaniṣad calls the ultimate reality Sat — being, (san-matram hibrahma.)
Since nothing is without reason there must be a reason why something exists rather than nothing. There is something; there is not nothing.
The world is not self-caused, self-dependent, self-maintaining. All philosophical investigation presupposes the reality of Being, asti-tva-niṣṭhā. 
BEING denotes pure affirmation to the exclusion of every possible negation.
Non-being is sometimes said to be the first principle (TU 2:7). It is not absolute non-being but only relative non-being, as compared with later material existence. In fact both Being and Non-being arise together since they are mutually constitutive of each other – two sides to the same coin.
 There is a familiar distinction between nāstika and āstika. The nāstika thinks that nothing exists except what we see, feel, touch and measure. The āstika is one who holds with R.V. X. 31. 8. Naitāvad enā paro anyad nāsti — there is not merely this but there is also a transcendent other.
Author: Rami Sivan, Priest, Dharma teacher, counsellor, Gov. Advisor (1998-present)
May 1st 2020