Under Way

http://commons.wikimedia.org/wiki/File:Claude_Monet_-_The_Gare_Saint-Lazare,_Arrival_of_a_Train.jpg

A stationmaster waves his flag, and a train begins to move. There is a last moment of rest, and a first moment of motion.

But this is a problem. If time is infinitely divisible, then there is a moment between these two moments. Is it a moment of rest or of motion?

(From Robin Le Poidevin, Travels in Four Dimensions, 2003.)