The Ascension, understood in terms of human chronology and human understanding, ends the story of Jesus' life on earth, that life which begins with the joy of Nativity. How far we have travelled from the innocence of the crib, the angels and the shepherds singing together.
With every stage of Jesus' life we are drawn into a deeper and deeper mystery, and are faced with new challenges.
His teaching, for instance, if taken as seriously as it should be, tells us to love our enemies. Enemies - and how often do we break even old friendships for a few careless words, spoken in a moment of emotion? How difficult it is to forgive, let alone forget, trivial offences.
His miracles: How difficult to believe in them unreservedly and, even more, tell others about them without an excuse of "Well, we do not know, really. Maybe Lazarus was not quite dead in the literal sense. Maybe he was in a coma.
"Maybe the paralytic experienced an emotional shock at meeting the famous rabbi and recovered naturally. Maybe the bread and fish were just symbols of the future kingdom of plenty."
Then comes the resurrection, a huge and, for many, insurmountable challenge. This is not about the Star of Bethlehem leading the Magi, a story so comfortably like a legend to the "modern and enlightened" mind that few bother to contest it.
'He was lifted up and a cloud took him out of their sight.'
It is about real red blood pouring from more than 100 wounds, about nails in the wrists and the feet, about the solid Roman spear piercing the heart. How could a man live again, having been killed by such experts in painful executions as the Roman soldiers were?
A historical man, too, not a mythical Greek or Roman hero, not Dionysus torn by evil Titans, not Attis bleeding under the tree, not Osiris hacked into pieces by his wicked brother Seth.
Jesus was a historical man yet he was also a man who, after death, would walk through the closed door and greet his friends, who had to reveal himself to his disciples walking beside him to Emmaus or else they would not recognize him, a man who would eat in front of all.
The easier solution to this challenge is to file away the ancient men and women of Jesus' time as somewhat silly-minded, naïve and superstitious.
The truth is that those people knew more about death and dying than we do. They held their dying in their arms, they washed the bodies, they buried them with their own hands. We avoid these tasks. We are hardly experts on death so we cannot be doubters of resurrection.
Now all who believe in him face the last challenge, the Ascension. One might have supposed that Jesus, alive again, would establish his kingdom. I am sure his best friends and disciples expected him to do it. I know I would.
So many things would have been solved, so much suffering spared. The victory of God would have been so obvious, the power of the wicked broken in the eyes of all.
Why did Jesus remove his visible presence from us? Why cannot I see his smile, touch his hand, bury my face in the folds of his robe when I am afraid or sad? Why did he choose such a vulnerable form - the host? Such questions will remain unanswered until we die.
Some that come to my mind, untrained in God's mysteries, sound almost ridiculous. What if Jesus trusted us? What if he, the God, risked rejection of his unbelievable love and sacrifice because he desired our love and our fidelity?