John 20:18
“She therefore departs, bearing these tidings to the disciples.”
So great a good is perseverance and endurance. But how was it that they did not any more grieve when He was about to depart, nor speak as they had done before? At that time they were affected in such a way, as supposing that He was about to die; but now that He was risen again, what reason had they to grieve? Moreover, Mary reported His appearance and His words, which were enough to comfort them. Since then it was likely that the disciples on hearing these things would either not believe the woman, or, believing, would grieve that He had not deemed them worthy of the vision, though He promised to meet them in Galilee; in order that they might not by dwelling on this be unsettled, He let not a single day pass, but having brought them to a state of longing, by their knowledge that He was risen, and by what they heard from the woman, when they were thirsting to see Him, and were greatly afraid, (which thing itself especially made their yearning greater,) He then, when it was evening, presented Himself before them, and that very marvelously. And why did He appear in the “evening”? Because it was probable that they would then especially be very fearful. But the marvel was, why they did not suppose Him to be an apparition; for He entered, “when the doors were shut,” and suddenly. The chief cause was, that the woman beforehand had wrought great faith in them; besides, He showed His countenance to them clear and mild. He came not by day, in order that all might be collected together. For great was the amazement; for neither did He knock at the door but all at once stood in the midst, and showed His side and His hands. At the same time also by His Voice He smoothed their tossing thought, by saying,
Source: Homilies on the Gospel of John (New Advent)