An accident is seen as "unexpected" only from the perspective of creatures in this world, but not for whatever entity planned or decided it. The author questions why God allows accidents and unexpected incidents to happen to some people but not others, seeing it as unfair partiality. However, there may be reasons for this that we cannot understand until we reach eternity, and not through the journey to get there. Until then, accidents will remain "unexpected incidents" that currently have reasons unknown.