One of the most widely used terms in the Hindu religious literature, the word ‘Brahman’ has several senses: the Vedas, hymns of praise, a priest, one of the four principal priests in a sacrifice representing the Atharvaveda, a brāhmaṇa, tapas or austerity, God the Creator (the four-faced Brahmā) and the Supreme Spirit or the Absolute. However it is in the last sense that it is extensively used, and hence needs greater explanation.
An oft-occurring theme in the Upaniṣads is the assumption and search for the unity in diversity. ‘What is that, by knowing which, everything else is known?’—is a typical question that is raised in them (Muṇḍaka Upaniṣad. 1.1.3; Bṛhadāraṇyaka Upaniṣad. 4.5.6; Chāndogya Upaniṣad 6.1.3). The sages of the Upaniṣads realized in the depths of their mystical experience, that there was a basic reality underlying the entire universe of multiplicity, the One without a second, and called it ‘Brahman’.
The word ‘Brahman’ is derived from the root ‘bṛh’ (‘to grow,’ ‘to burst forth’) and hence means that which is immense and that from which everything else has come out. In other words, it is from Brahman that this world has evolved, it is in Brahman that it rests even after this evolution and again, it is to that Brahman that it returns at the time of involution. ‘Sṛṣṭi,’ ‘sthiti’ and ‘laya’ or ‘pralaya’ are the three words generally used to indicate these processes. Brahman, however, remains unaffected by this evolution or involution and is ever full and perfect (pūrṇa) in itself.
The intrinsic power of Brahman with which it creates this world, sustains it and withdraws it into itself, is called ‘māyā’.
Since creation is only an evolution of Brahman—which evolution is considered as only apparent and not real, according to some schools of Vedānta—Brahman continues to exist in it as the immanent reality. Thus it is both transcendent and immanent simultaneously.
Quite often, the Upaniṣads use the word ‘Ātman’ as synonymous with Brahman. Sat, Akṣara and Bhūmā are some of the other terms used to indicate Brahman.
The evolution of the world from the Brahman/Ātman is generally traced as follows: From the Brahman evolves ākāśa (ether); from ākāśa comes vāyu (wind) from vāyu comes agni (fire), from agni comes ap (water) and from ap comes pṛthivī (earth). Vegetation and then, life (including the human beings) evolve out of this earth.
In the Vedāntic works based on the Upaniṣads, four aspects of Brahman have been put forth: the Absolute called Brahman, the creative spirit Īśvara (Lord, God), the world-spirit Hiraṇyagarbha and the world, Virāj.
The totality of creation which is none other than Brahman in essence, is the Virāj. When Brahman is thought of as the spirit moving everywhere in the world, it is called Hiraṇyagarbha. When conceived as the personal God engaged in the act of creation, protection and destruction of the world, it is called Īśvara. When believed to be established in itself independent of any creation, it is Brahman, the Absolute.
The Reality is not a sum of these. It is an ineffable unity in which these conceptual distinctions are made.
Brahman, the Absolute, is unique and different from all that we know and experience here. Hence it can be predicated only in negative terms, ‘neti, neti,’ ‘not this, not this’. This should not mislead us into thinking that it is a non-entity. While it is non-empirical, it is also inclusive of the whole empirical world. And, it has an essential nature of its own: ‘sat’ or being, ‘cit’ or consciousness and ‘ānanda’ or bliss. These are not its characteristics but are different phrases for the same being: self-being, self-consciousness and self-delight.
There are also passages in the Upaniṣads that describe Brahman as Puruṣa or the Supreme Being. He is the Aupaniṣada-puruṣa, the Being described in the Upaniṣads and known only through them. He is the Hiraṇmaya-puruṣa, the golden Being, the Supreme Soul existing in the āditya or the sun (vide Bṛhadāraṇyaka Up. 3.9.26; Chāndogya Up. 1.6.6), He is the Mahān-puruṣa, the great Person, by knowing whom one can transcend death (Śvetāśvatara Up. 3.8). He is greater than the greatest and smaller than the smallest (Kaṭha Up. 1.2.20). He has pervaded everything and has established himself as the inmost Self in all the beings (Īśāvasya Up. 1; Kaṭha Up. 2.2.12). He is the Lord of the lords and God of the gods. There is none that is superior to him or even his equal (Śvetāśvatara Up. 6.7-9). He bestows boons on his devotees that worship him (Kaṭha Up. 1.3.2).
The Vedāntic schools of Rāmānuja (A. D. 1017-1137) and Madhva (A. D. 1238-1317) identify Brahman with Viṣṇu/ Nārāyaṇa.