“Consciousness is the knowing of knowing.” — Jean-Paul Sartre, Being and Nothingness (1943)
“The essence of consciousness is to be conscious of itself.” — Hegel, Phenomenology of Spirit (1807)
“To be conscious of being conscious — that is the human difference.” — Pierre Teilhard de Chardin, The Phenomenon of Man (1955)
“The animal knows; man knows that he knows.” — Pierre Teilhard de Chardin, The Phenomenon of Man
