Described in chandogya upnasad 6.8.7 confirms that tat twan asi means "i am you and you are me" which has the meaning that "i" as the essence of the most beginning in the universe and "you" is all creation from god himself.
Ring chandogya upanisad 6.8.7 kategesang indik tat twam asi mateges “tiang punika ragane, ragane punika tiang” tur maduwe arti “aku utawi tiang” dados sane pinih utama ring jagate tur “engkau utawi ragane” inggih punika sami pakardi ida sang hyang widhi wasa ring jagate puniki.