Self Realisation = Brahman

Brahman (bráhman-, nominative bráhma ब्रह्म) is a concept derived from the verb "Brah" (to grow), and connotes "Great Origin". Upanishad says: That supreme Brahman is infinite, and Brahman is a condition or state of mind which is infinite. “The infinite proceeds through knowledge, realizing the infitude of the infinite”.

By definition, Brahman is the Unchanging, Infinite, Permmanent, and Transcendent reality which is the “Divine Ground” of all Matter, Energy, Time, Space, Being, and everything beyond in this Universe. [1]

Rig Veda explains; Brahman is the the source of the “Hiranyagarbha” (Golden Womb or “The Creator” God-Brahmā). Composers of the Upanishads' wrote-that the liberated soul conforms his identity with the Brahman, as his true self.

“Brahman” is different from "Brahmin" (what we call as the priests or holy men), in fact word "Brahmin" came into being from "Brahman" due to the confusion in pronunciation between the terms by modern English translators and can be dated back to the translation of the Upanishads into modern English in late 17th century.

Sages, who wrote Upanishads' fully realized “Brahman, as the reality”, behind their own being and of everything else in this universe. They were thus Brahmins in the true sense of the word. They were not Brahmin by birth but because of their self realisation and by virtue of being liberated souls. However, later on Brahmin came to be identified with the highest of the four castes, the Brahmins, who by virtue of their purity and priesthood held themselves high and as proprietors of rituals, without any effort for actual self realization, and even void of Vedantic knowledge. Maharishi Valmiki, Parashuram, or Gautam Siddhartha weren't Brahaman but after self realisation, became one. "Kautliya, the guru" of emperor Chandragupt Maurya was also not Brahman by birth but because of his virtues.

Imagine a person who is blind from birth and has not seen anything. Is it possible for us to explain to him what light is like? Is any amount of thinking or reasoning on his part ever going to make him understand the sensation of light? In a similar fashionl the idea of Brahman cannot be explained or understood through material reasoning or any form of human communication. Brahman is like light; those who can sense it cannot explain or argue with those who have never sensed it.

“Brahman” is Absolute Reality or the universal substrate and must not be confused with "The Creator God Brahmā". Brahman is Eternal, Omnipotent, Omniscient, Omnipresent, and ultimately indescribable in human language. “Brahman” is the source and essence of the material universe. The initial “unmanifest state” of singularity of the universe. It is also described as beyond-Being and Non-Being.Brahman is also not restricted to the usual dimensional perspectives of Enlightenment, Moksha, Yoga, Samadhi, Nirvana, etc. Mahayana, the concept of Buddha Nature is also closely related to the “Self realisation of Brahman”. The closest interpretation of the term can be found in the Taittariya Upanishad (II.1) where Brahman is described as "satyam jnanam anantam brahman" ("Brahman is the nature of truth, knowledge and infinity"). Thus, Brahman is the origin and end of all things, material or otherwise. Brahman is the root source and Divine Ground of everything that exists, and does not exist. It is defined as unknowable and Satchitananda ("Truth-Consciousness-Bliss"). Since it is eternal and infinite, it comprises the only truth.

In Veda’s and Upanishad’s; it is said, "Ekam Satya (Truth is one) and all that is true is Brahman". This also explains, the Hindu view that "All paths lead to the one Truth, though many sages and religions call upon it by different names."Thus the goal of a true Hindu is by all means is to realise that the soul is nothing but Brahman.

Several great sayings, indicate the "universality of the principle of Brahman";

"Brahman is knowledge" ayam ātmā brahma [2]

"The Self (or the Soul) is Brahman "aham brahmāsmi [3]

"I am Brahman" tat tvam asi [4]

"Thou are that" sarvam khalv idam brahma [5]

"All this that we see in the world is Brahman", sachchidānanda brahma [6], [7]

Summary:
"Brahman is existence, consciousness, and bliss" not to be confused with: Brāhmaņa (masculine, pronounced as /brα:h mə Ņə/) in the mantras—an integral part of the Vedic literature. Brāhmaņ (same pronunciation as above), means priest; the word is usually rendered in English as "Brahmin". This usage is also found in the Atharva Veda.

1. Supreme Lord (Ishwara), in Advaita, is actually a partial worldly manifestation with limited attributes of the ultimate reality which is "the attributeless Brahman".

2. Devas, the celestial beings of Hinduism, which may be regarded as deities, demi-gods, spirits or angels.

3. Upanishads identify "the Atman", (the inner essence of the human being), with Brahman, the Great Spirit.

4. Advaita and Dvaita philosophies understand Brahman as one with infinite auspicious qualities wherein the ultimate reality is expressed as Nirguna Brahman (formless, attributeless).

5. All forms of Gods including Vishnu and Shiva are different aspects of God in personal form (Saguna Brahman i.e. God with attributes).

6. God's energy is known as Devi, the Divine Mother.

References:
1. Brodd, Jefferey (2003). World Religions. Winona, MN: Saint Mary's Press.
2. Brihadaranyaka Upanishad 4.4.5,
3. Brihadaranyaka Upanishad 1.4.10,
4. Chhāndogya Upanishad 6.8.7 et seq.
5. Chhāndogya Upanishad 3.14.1
6. Nrisimhauttaratāpini, cited in Swami Nikhilananda, The Upanishads: A new Translation Vol. I. 7. In the Bhagavad Gītā, Krishna also describes the nature of Brahman. For example, he says "And I am the basis of the impersonal Brahman, which is immortal, imperishable and eternal and is the constitutional position of ultimate happiness" (brahmano hi pratishthaham...) B-Gita (As-it-Is) 14.27 Translation by Bhaktivedanta Swami Prabhupada

Humble acknowledgement: (Several resources over the internet were used in the prepration of this entry)