Sartre described this on a more abstract level in his essay "La transcendence de l'ego: Esquisse d'une description phénomenologique"[0], which essentially says

Sartre described this on a more abstract level in his essay "La transcendence de l'ego: Esquisse d'une description phénomenologique"[0], which essentially says that the active level of consciousness can never be reflected upon because the moment we reflect upon it it becomes passive, being reflected upon by a higher level of consciousness. [0] english wp article about the essay: https://en.wikipedia.org/wiki/The_Transcendence_of_the_Ego https://en.wikipedia.org/wiki/The_Transcendence_of_the_Ego