ˈɛkhɑːɹt tˈoʊl fˈɜːst ɛksplˈoːɹd ˈiːɡoʊ ɪnðə pˈaʊɚɹ ʌv nˈaʊ, wˌɛɹ hiː dʒˈʌkstɐpˌoʊzd fˈɔːɹm aɪdˈɛntᵻɾi ænd ˈɛsəns aɪdˈɛntᵻɾi.
Eckhart Tolle first explored ego in The Power of Now, where he juxtaposed form identity and essence identity.