It was the ancient Greeks who in lyric poetry were the first really to discover what we know today and take for granted as the self. It is difficult for us now to imagine how that discovery must have felt like a great revelation.
Abad, Gemino, "Early Greek Lyric Poetry: The Cry of the Self" (2003). Research Collection School of Social Sciences. Paper 16.
Available at: http://ink.library.smu.edu.sg/soss_research/16