Brahman the highest of the four Hindu castes. At the same time they also believe in the existence on one Supreme God, whom they call variously as Paramatma (Supreme Self), Parameshwar (Supreme Lord), Parampita (Supreme Father), Iswara, Maheswara, Bhagawan, Purusha, Purushottama, Hiranyagarbha and so on.

It is this Absolute which is called Brahman. But these are only like the 'quantum particles' of the material world and have an ambiguous reality; at their root lies Brahman or Oneness and this is what gives them their reality. Whatever it is, the fact is that Brahman of the Upanishads is more appealing to the seekers of Truth and Knowledge than seekers of material gains.

We only hear of fire sacrifice, later to be called Nachiketa fire, to attain Him, which was taught to the young Nachiketa by Lord of Death, but lost in the course of time to us. Perhaps the sacrifice was more a meditative or spiritual practice involving the sacrifice of soul consciousness than a ritual worship.

Brahman or the Supreme Self is beyond time and space, causation. Like an oxidized metal, that needs to be cleaned consistently and daily, so also stay grounded on that One Brahman in your pure intellect, represented by 'Om' and the entire universe dissolves and Brahman alone is, like the camphor that dissolves.

Hence this means that our 'I' is the Absolute Brahman itself. He is Vastu, Atman or Brahman or the Supreme Self is the hidden treasure. Mind always runs after pleasure because it is born of Ananda (Brahman). This is the form that manifests the essence He is pervading everywhere and The Lord embodies the Highest Knowledge of Brahman present in the core of the Vedas.

Generally unknown and mysterious to the ordinary masses, Brahman of the Upanishads remained mostly confined to the meditative minds of the ancient seers who considered Him to be too sacred and esoteric to be brought out and dissected amidst public glare.

It considers the Vedas to be eternal, timeless and contemporaneous with Brahman. Brahman, associated with maya, also the cause is saguna Brahman, also called Isvara. That is, the totality of human existence: all thought and love, and hopes and desires, all perceptions of afterlife and governance of the present, all fears and hatred bound as one with love and trust and death.