There are a lot of very influential pictures/metaphors concerning time, e.g., the idea of time as passing, as a stream that flows or as a sea over which we advance. Usually we think that time is something one-dimensional. Only in the case of time-branching do we accept two-dimensional graphical pictures as representations of time. The theory of relativity illustrates the advantages of replacing the two separate notions of space and time by a unified notion of space-time. Therefore, we obtain — with three space dimensions and one for time — a four-dimensional space-time manifold. There are many investigations of natural language tense-expressions by linguists assuming that negations of temporal sentences can be represented as a time switch. Using a straight line as the picture of time a time switch is nothing else than a rotation of a segment of this line around a given point of the same line. This picture depends on the presupposition that time must be represented as a continuum.