What can we say about a concept like the ātman when its principal feature is its apparent indefinability and impersonal nature? Initially we could do worse than utilise Jurewicz's definition of the term, based mainly on Ṛgvedic sources: ‘This word is used to denote the essence of an entity, the whole body (which ensures personal identity and existence), its most important parts, which are the head (which ensures personal identity and existence – here and in the afterworlds) and the breath (which ensures the existence of a living being)’. But moving on to the Upaniṣads, the final texts in the Vedic corpus, we find a systematisation and an impersonalism in the conceptual development of the ātman idea. We are confronted in the Upaniṣads with what individual teachers say about it, rather than what it is, because what it is defies easy description in words and this has to be taken as the axiomatic commencement point for any study of it.

In looking at the possible origin of the idea of such an essence, we could draw upon Proferes, who has recently argued for ideas of universal sovereignty, associated with the sacred fire of the household, clan and tribe, where the rājā's fire combines the parts with the whole. It becomes a political metaphor that could be used to develop a metaphysical idea of unity within diversity. For Proferes,

He gives a series of examples from the two earliest Upaniṣads, in order to argue that it is the sense of ‘unlimitedness’ associated with Vedic ideals of freedom that becomes disconnected from theories of kingship and translated into a metaphysical idea of freedom from all limitations.