But let us observe how this Jew of Celsus asserts that, “if this at least would have helped to manifest his divinity, he ought accordingly to have at once disappeared from the cross.” Now this seems to me to be like the argument of those who oppose the doctrine of providence, and who arrange things differently from what they are, and allege that the world would be better if it were as they arrange it. Now, in those instances in which their arrangement is a possible one, they are proved to make the world, so far as depends upon them, worse by their arrangement than it actually is; while in those cases in which they do not portray things worse than they really are, they are shown to desire impossibilities; so that in either case they are deserving of ridicule.
And here, accordingly, that there was no impossibility in His coming, as a being of diviner nature, in order to disappear when He chose, is clear from the very nature of the case; and is certain, moreover, from what is recorded of Him, in the judgment of those who do not adopt certain portions merely of the narrative that they may have ground for accusing Christianity, and who consider other portions to be fiction. For it is related in St. Luke's Gospel, that Jesus after His resurrection took bread, and blessed it, and breaking it, distributed it to Simon and Cleopas; and when they had received the bread, “their eyes were opened, and they knew Him, and He vanished out of their sight.”
Source: Against Celsus (New Advent)