The Temple, as Jesus knew it, was one of the great ancient monuments. It had the reputation of being the most beautiful building in the whole world, and the largest and most imposing structure for hundreds of miles in any direction. It inspired awe. The disciples admire its glory. Jesus predicts its end. The disciples assume, here, that there’s going to be a catastrophic event that will cause the Temple to be destroyed and, as part of this, those who follow Jesus will be put at great risk. Jesus knows that he will not always be with them. He knows that they will face what he has faced, and all because of their allegiance to him. He knows, far more than they do, what we might nowadays call the cost of discipleship.