The story is told by a sequence of scenes. Each scene can be seen as sequence of processes which involve actors. These processes may be concurrent. Thus time plays an important role - one could create completely different stories by altering the time order of a given path. Figure 3.1 gives an example of such a sequence.
Time introduces history - there is past and future.
Especially, having a past makes complex situation easier to grasp. Cause and effect relationships and transformations like growing, changing properties, morphing into other shapes become evident without additional hints.