 Many cases, however, are less straightforward, and it is not always easy to distinguish when entities stand in ontological rather than causal relations. We could argue that the formation of the Triple Alliance is only causally related to the war because it took place long before the war began. But temporal remoteness is not always good evidence. Even if causes must always precede their effects, identifying causally related events is complicated by the fact that events extend over long periods of time. (The weather in January 1916 is causally and not ontologically related to World War I, although the war stretched on before and after that month.) Furthermore, there might be instantaneous or even backward causation (see entry on  backward causation).