Once Again Through Time Ia

I expect that Poul Anderson fans will understand if I say that Anderson presents:

a single immutable timeline with temporal corridors in The Corridors Of Time;

a single immutable timeline with psychic time travelers in There Will Be Time;

a single mutable timeline in his Time Patrol series;

multiple timelines in his Old Phoenix sequence.

However, the phrase, "...single mutable timeline...," is unsatisfactory. We describe the monobloc and the mutually receding galaxies not as different universes but as successive phases of a single universe. That is clear enough. In Anderson's "Delenda Est," the Danellian history is succeeded or replaced by the Carthaginian history which in turn is succeeded or replaced by the restored Danellian history. We describe these histories not as successive phases of a single timeline but as successive timelines. This would be merely a terminological difference. Nevertheless, we in fact use the terminology of successive timelines, not of successive phases of a single timeline. Again, in the concluding Part of The Shield Of Time, the Danellian history is replaced by the alpha history which is replaced by the beta history which is at last replaced by the restored Danellian history. We think of successive timelines, not of a single timeline changing through successive phases.

Thus, in the Time Patrol series, multiple timelines succeed each other along a second temporal dimension whereas, in the Old Phoenix sequence, multiple timelines coexist along a fourth spatial dimension.