Ātman

Lesson 9 was about Brahman, the ground of everything, approached from the outside — the largest question the Upaniṣads ask. This lesson turns to the other end of the same enquiry, and it is a much more personal one: what is a person?

The word they use is ātman, and the first surprising thing about it is how unremarkable it is.

The lexicon traces it to roots meaning to breathe, and gives "the breath" as its earliest attested sense in the Ṛgveda. From there it becomes the principle of life and sensation, then the individual self. And it never stops being ordinary: ātman is also the everyday Sanskrit reflexive pronoun. It is the word in "she struck herself" and "he did it himself" — for all three persons and all three genders.