also: おぬ
pronoun
Archaic first-person pronoun, equivalent to modern 自分 or 私. Used in classical Japanese and occasionally in modern literary or poetic contexts. The reading おの is standard; おぬ is a rare variant.
己を知る者は賢者なり。
He who knows himself is wise.
己が道を進むのみ。
I simply follow my own path.
The historical derivation is uncertain. 己 is a native Japanese pronoun with ancient roots, appearing in classical texts. The kanji 己 is conventionally associated with the meaning 'self'.