The Tribulation must have been an incredibly violent set of events that essentially brought a cataclysmic end to the world as people knew it back then. The Waknuk people know about fires, floods, earthquakes, and other natural disasters, and they know that those things existed in biblical times as well. The Tribulation, we are told, was like all of those things happening at once, on an unheard-of scale.

The general accepted thought is that God must have sent the Tribulation as punishment for whatever humanity was doing at the time. Uncle Axel questions the validity of this argument. He doesn't understand how or why the Tribulation allowed for the current deviations. He flat-out says this doesn't make sense and is beneath the wisdom of God. The current Waknuk thinking is that they also have to try to recreate the world that the Old People of years before had. Uncle Axel questions this goal and brings up the possibility that the return of those conditions might trigger another Tribulation.

And after a bit they might begin to say: "Are we right? Tribulation has made the world a different place; can we, therefore, ever hope to build in it the kind of world the Old People lost? Should we try to? What would be gained if we were to build it up again so exactly that it culminated in another Tribulation?"