Conventional: Something that seems real but is not. A belief about or perception of reality that is false. ACIM: The Course expands this common definition to include anything outside of Heaven, anything that is imperfect, finite or painful. This includes any object, situation or event in the world of time and space, including time and space themselves. It also includes our thoughts, beliefs and perceptions while in this world, which are misrepresentations of reality. Truth and illusion have nothing in common; we must choose one or the other. The ego tells us that our only choice is between illusions, deciding which ones we like best. Yet the Holy Spirit teaches that all illusions are equally unreal (see no order of difficulty in miracles) and that all must be brought to truth where they will vanish (see bringing darkness to light). forgiveness is an illusion, but it is the only illusion that leads to the end of illusions, rather than breeding more. See dream, fantasy.