§ 29. With regard to causality, we start with the logical form of a hypothetical judgment. We can make a subjective judgment of perception and say, "If the sun shines long enough on a body, then the body will become warm." This, however, is an empirical rule that is valid merely of appearances in one consciousness. If I want to make an objective, universally valid hypothetical judgment, however, I must make it in the form of causality. As such, I say, "The sun is the cause of heat." This is a universal and necessary law that is valid for the possibility of objective experience. Experience is the valid knowledge of the way that appearances succeed each other as objects. This knowledge is expressed in the form of a hypothetical [if/then] judgment. The concept of causality refers to thoughts and statements about the way that successive appearances and perceptions are universally and necessarily experienced as objects, in any consciousness.