
Gregory the Great
Catena Aurea · Matthäusevangelium 24
Watch therefore: for ye know not what hour your Lord doth come. But know this, that if the goodman of the house had known in what watch the thief would come, he would have watched, and would not have suffered his house to be broken up. Therefore be ye also ready: for in such an hour as ye think not the Son of Man cometh.
(Hom. in Ev. ii, 3.) To watch is to keep the eyes open, and looking out for the true light, to do and to observe that which one believes, to cast away the darkness of sloth and negligence.