Brahman, Almighty, Supreme Being, Ishvara or Purusha is “Neti-Neti” means “neither this, nor that". .It is found in the Upanishads helping a person to understand the nature of the Brahman by negating everything that is not Brahman. One of the key elements of Jnana Yoga practice is often a "neti neti search." The purpose of the exercise is to negate all objects of consciousness, including thoughts, Intellect and the mind, and to realize the non-dual awareness of reality, which cannot be defined.
Brahman (not to be confused with Brahma - one of the three faces of the Hindu Trinity) is said to be the Ultimate Reality - the unchanging or absolute truth behind ever changing phenomenal world. It is beyond mind and its limitations. Consciousness is the awareness of its existence (External or Internal).
This Truth or Satyam is elucidated in Hindu Scriptures in depth. It has nothing to do with the common truthfulness which is related to ethics or morality.
Truth or Satyam:
Ritam or Orderliness:
In the Vedic religion, Ṛitam is the principle of natural order which regulates and coordinates the operation of the universe and everything within it. Satyam is Truth and Ritam is the law that governs the working of that Truth. So, although both words basically mean the same, there is still a subtle difference between the two.
The Supreme Being (Purusha) holds together both Ritam and Satyam in blissful harmony. The Vedic Seers of yore reconciled the relativity of Ritam and Satyam in the concept of “Dharma", that is “Purusha”. In Vedic context Ritam and Satyam are the two inseparable aspects of the “Purusha” Who is the Whole Unified Universe.
The first hymn, addressed to Agni, suggest the central conception of truth. Truth is truth of divine essence, not truth of moral sensation and appearance. It is “Satyam”, truth of Bring; it is its action Ritam, i.e., right, - truth of divine being regulating right activity both mind and body; it is brhat, i.e., large as opposed to the consciousness of sense-mind which is founded upon limitation. The one is described as bhuma, the large, the other as alpa, the little. Truth consciousness is Mahas which also means the great, the vast. We have for the instruments the senses, the sense-mind (manas) and intellect working upon their evidence, so for the truth-consciousness there are corresponding faculties, - drsti, sruti, viveka i.e., the direct vision of the truth, the direct hearing of its word, the direct discrimination of the right.
Ritam is the symbol of dynamic orderliness. It is the principle of cosmic harmony. It is the Natural Law underlying all that moves and moves not.
In Rig Veda (10.190.1) -
ऋ॒तं च॑ स॒त्यं चा॒भी॑द्धा॒त्तप॒सोऽध्य॑जायत । ततो॒ रात्र्य॑जायत॒ तत॑: समु॒द्रो अ॑र्ण॒वः ॥
ऋ॒तम् । च॒ । स॒त्यम् । च॒ । अ॒भी॑द्धात् । तप॑सः । अधि॑ । अ॒जा॒य॒त॒ । ततः॑ । रात्री॑ । अ॒जा॒य॒त॒ । ततः॑ । स॒मु॒द्रः । अ॒र्ण॒वः ॥
“Truth (of thought) and truthfulness (of speech) were born of arduous penance, thence was night generated, thence also the watery ocean.”
Hence, RV 10.190.1 indicates that Ritam and Satyam first arose from tapas (fervour / heat) and that the night (ratri) and the ocean were established after these.
Similarly, RV 10.85.1 states that Satyam upholds the earth (satyenottabhitā bhūmiḥ) while the Adityas stand secure because of the Ritam.