When she is witnessing the Twin Towers collapse, Oskar's grandmother says, "Every moment before this one depends on this one" (232).
Oskar's grandmother gives her perspective on her life: "Each day has been chained to the previous one. But the weeks have had wings. Anyone who believes that a second is faster than a decade did not live my life" (181). This idea also connects to the theme of Time.
"Everything in the history of the world can be proven wrong in one moment." (232)
This topic is linked to both the Significance and the Insignificance of people. Choices or lack of them decide the degree of significance or insignificance of moments and lives.
Oskar also alludes to digging up his father's grave throughout the book, and all the events seem to be leading up to that particular event as a grand finale. Had the book gone a different way, it almost feels as if the conclusion would have been entirely different.