 Since, by definition, two items can only be ET-simultaneous if one is temporal and the other eternal, and since any given item is only one of these, ET-simultaneity is not reflexive; in fact, it never holds between an entity and itself. Nor is it transitive; in fact, when x and y are ET-simultaneous and y and z are too, x and z never are. The non-transitivity of ET-simultaneity is needed to solve a pressing problem. If t is simultaneous with eternity, and eternity is simultaneous with \(t'\), then t is simultaneous with \(t'\). So, all times collapse into one: