Sartre's Being and Nothingness focuses on the concept of consciousness, which Sartre terms the For-itself, in relation to being, which he calls the In-itself. Sartre contrasts the For-itself with the In-itself, which is full, complete, and without nothingness. He then examines how consciousness, through negation, reveals being to itself, leading to concepts such as lack, possibility, and temporality. Sartre also discusses the relationship between consciousness and the body, suggesting that the body acts as a medium for consciousness to experience the world and that the body itself is subjected to the same nihilating processes as consciousness.