In Sartre's opinion, consciousness does not make sense by itself: it arises only as an awareness of objects. Consciousness is therefore always and essentially consciousness "of something", whether this "something" is a thing, a person, an imaginary object, etc. Phenomenologists often refer to this quality of consciousness as "intentionality". Sartre's contribution, then, is that in addition to always being consciousness "of something", consciousness is always consciousness "of itself". In other words, all consciousness is, by definition, "self-consciousness". By "self-consciousness", Sartre does not mean being aware of oneself thought of as an object (e.g., one's "ego"), but rather that, as a phenomenon in the world, consciousness both appears and appears "to itself" at the same time. By appearing to itself, Sartre argues that consciousness is fully transparent; unlike an ordinary "object" (a house, for instance, of which it is impossible to perceive all of the sides at the same time), consciousness "sees" all aspects of itself at once. This non-positional quality of consciousness is what makes it a unique type of being, a being that exists "for itself".