twelve hours = The Roman and the Jewish days were divided into 12 equal hours from sunrise to sunset. The actual amount of time in an hour would vary directly with the amount of daylight in a day, which would vary from season to season. In Palestine the variation is from 14 hours and 12 minutes in the summer to 9 hours and 48 minutes in the winter. What Jesus means by twelve hours, is the entire day and all the time contained therein.

What this means is that we have enough time to do everything God has for us to do and that no enemy or circumstances can shorten our “day”. But it also means that there are only twelve hours in a day and they cannot be extended. We must make the most of the time we have. Christ, the Light of the world, is only present among men for a time; when He is withdrawn, they must walk in darkness.