Rig Veda 10.125.8 is unique as it is one of the rare occasions in the Vedas where a mantra is spoken in first-person. Such mantras are categorised as directly relating to the Self, where the worshipper is identical with the deity being worshipped and the illusion of separation is seen through.
In Rig Veda 10.125.8, it is declared that,
I breathe forth like the wind, giving form to all created worlds. Beyond the heaven, beyond this earth, so vast am I in greatness.
This depicts the seer of the mantra’s realisation of Brahman. They observe themselves as that and all as existing within them. They have realised it as the source of one’s being and all things. It is from Brahman that all (form) is ‘breathed forth’. Established in the awareness of the Self, one traces them to their source, where there is no duality such as ‘heaven and earth’.
The breath being spoken of is not literal, but used as a way of understanding how the universe appears separate. The meaning of Brahman is tied to this notion of breath, as the root of the word, ‘brih‘, means “to expand or breathe”.
The idea of breathing or exhaling as the appearance of form is later found in the Upanishads. Brihadaranyaka Upanishad 2.4.10 states,
As smoke billows out in all directions from a fire that has been laid with damp fuel, so is everything breathed out from this great being.
This is the same knowledge whose realisation is conveyed in Rig Veda 10.125.8. Just as the smoke created by the fire is not separate from it, the world is not separate from the Self or Brahman.
In his commentary to Brihadaranyaka Upanishad 2.4.10, Shankara elaborates,
the universe, at the time of its origin as also prior to it, is nothing but Brahman. As before the separation of the sparks, smoke, embers and flames, all these are nothing but fire, and therefore there is but one substance, fire, so it is reasonable to infer that this universe differentiated into names and forms is, before its origin, nothing but Pure Intelligence. [1]
It is the undifferentiated universe, prior to name and form, which is nothing but Brahman, that is the subject of Rig Veda 10.125.8 and Brihadaranyaka Upanishad 2.4.10. This is the essence of Advaita which all teachings point to the reality of.
Shankara goes on to say,
The differentiation of forms invariably depends on the manifestation of their names. Name and form are the limiting adjuncts of the Supreme Self, of which, when they are differentiated, it is impossible to tell whether they are identical with or different from It, as is the case with the foam of water. It is name and form in all their stages that constitute relative existence. Hence name has been compared to breath. By this statement it is implied that form too is like breath. [2]
This explains the association between form and breath. The breath and descriptions of creation refer to the differentiation of name and form or duality, what Shankara calls “relative existence.” It is relative because it depends on taking duality to be real and name and form separate from Brahman. When Advaita is realised, one sees that there is no differentiation and it was merely a projection of the mind. Therefore, no such creation ever took place in reality.
The Brihadaranyaka Upanishad and Shankara’s Bhashya shine light on Rig Veda 10.125.8. The “created worlds” are the distinctions we imagine which give the impression of duality being real. Saying, “I breathe forth” these worlds and my ‘”greatness” is beyond all, means the same as the mahavakyas, such as ‘I am Brahman’ [3]. It is the recognition that one is no different from ‘that’, the source of all name and form. In this way, not only does the mantra contain the truth of Advaita, but also the realisation itself.
[1] Brihadaranyaka Upanishad Bhashya of Shankara 2.4.10.
[2] Ibid.
[3] Brihadaranyaka Upanishad 1.4.10