According to Rig Veda, the entire universe was initially concealed in a condensed state, which had no form or shape. That was Brahman, the imperishable one, in a dormant state. (Brahman should not be confused with the God Brahma, of the Brahma-Vishnu-Mahesh trinity).
This primeval state of Brahman was neither matter nor non-matter, neither existent nor non-existent, neither being nor non-being, rather a sort of form of energy. Brahman has always existed. From this Brahman, and by its own volition/desire (out of its own internal energy/dynamics) the entire existence we see came into being.
Another interpretation that leads to the origin of the Earth and appearance of life in it can be that the entire existence always existed because Brahman is the existence. All that happened over the years was that the Brahman unveiled its existence, and so it is now apparent to our sense organs, while before we could not experience it. Brahman is not a god in the traditional sense. One should not confuse it with a living god.
The main characteristics of Brahman as described in the Vedanta are: Brahman is not a god. Brahman is neither a thing nor a person; It is not conscious in the way that we understand a conscious being; It does not take decisions on human affairs; It is neither living
nor non-living, or is both;
It is nirguna - it does not have any material qualities. It has no form. It is material as well as non-material.
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