10 You are troubled because you have found the double doors open, which a blind man in seeking his chamber is said to have unfastened. In this you learn that human watchfulness is no defence. Behold! One who has lost the gift of sight has broken through all our defences, and escaped the notice of the guards. But the Lord has not lost the guard of His mercy. Was it not also discovered two days ago, as you remember, that a certain entrance on the left side of the basilica was open, which you thought had been shut and secured? Armed men surrounded the basilica, they tried this and the other entrance, but their eyes were blinded so that that could not see the one that was open. And you know well that it was open many nights. Cease, then, to be anxious; for that will take place which Christ commands and which is for the best.
Source: Sermon against Auxentius (New Advent)