Jerusalem is the inner place where the great change happens, and the road up to it is the ascent within, the movement from the man ruled by his senses to the man who awakens as the creative power itself. Jesus, your own human imagination, goes before, because the imagining always leads and the outer self follows after. Amazement and fear come because the ordinary man dreads the death of who he has been, and this climb asks exactly that.
What is told the twelve is that the imagining must be handed over, felt as real, seemingly buried, and then raised in the world as fact. This is the pattern in every person, not a single event long ago. A state assumed and lived from is crucified into the flesh of your life and rises there. The self that says I am is walking that road now, and the outer man, half amazed and half afraid, is being led to his own awakening.