The parable assumes us that the owner of the house has received information that a thief will be coming during the night.1 In order to protect his home, he had to keep watch.2 If he knew that the thief was coming at a particular time, he would be on guard only at that time. He does not know when the thief is coming and so he must be on guard all the time.3
43 Sachez-le bien, si le maître de la maison savait à quelle veille de la nuit le voleur doit venir, il veillerait et ne laisserait pas percer sa maison.