In Our Lord's time almost every town was a walled one.
The exit way from each town was outfitted with benches
where the town-leaders could meet, deciding on the steps
to take for the town's safety. Foremost among their decisions
were those to close the gate when the town was threatened
by robbers or disease.
It sometimes happened that someone on a journey or out
working in the fields would return to find the town gate
firmly shut and barred. For such ones, the leaders provided a
narrow gate, hidden around the town's hill side. They also
stationed a gate-keeper who would only open to those who
were familiar to him.
Metaphorically, we strive to open through the narrow gate
when, instead of leaving our salvation open to chance, we
work at it day and night.