Every unit of length, no matter how small, has some specific extension; every
unit of time, no matter how small, has some specific duration. The idea of an
infinitely small amount of length or temporal duration has validity only as a
mathematical device useful for making certain calculations, not as a
description of components of reality. Reality does not contain either points or
instants (in the mathematical sense). By analogy: the average family has 2.2
children, but no actual family has 2.2 children; the “average family” exists
only as a mathematical device.