As it happens, I have just come from a session with our sophomores in High School discussing Nominalism and Realism. The Realists of the Middle Ages had a philosophy based on Plato which taught that the true reality was not the physical, material world which we think is ‘real’ but another invisible realm where things are more, not less real. C.S.Lewis was a Platonist (or Realist) in this sense. This is why in The Great Divorce the blades of grass puncture the feet of the spirit, and the apples are too heavy to pick up and he dare not go under a waterfall for fear of being crushed.
Nominalism (at the risk of being ridiculously simplistic) taught that there was no ‘real’ invisible realm, but this physical material world was the only reality. Protestantism was spawned by Nominalism, as was Deism, Scientism, Individualism and various other icky isms.
Back to the Ascension: if it is important that Jesus ascended physically then where did he go? If the Realists and Platonists are correct, he went to a realm which was not less physical than this one, but more physical. He entered into a dimension that was supra-natural not just supernatural. In other words, it was not just above nature, but it was dynamically more, far more than we can imagine natural, physical and material.
In one of his space trilogy books Lewis discusses this way of standing on one’s head about what is real or unreal. He says it is all a matter of perception. If you did not know that fog was insubstantial, and a man solid, then when you saw a man step through a bank of fog you might think he was so insubstantial as to move through solid material. So it is when an angel (or the resurrected Christ) step through a wall. It is not the resurrected Christ who is insubstantial–it is the wall. Christ is not less real or solid than the wall–he is more real and solid than the wall.
Likewise with his Ascension into heaven. He goes up into the clouds and disappears. This is not because he has become ethereal and ‘spiritual’ and less physical, but because he has moved into a realm in which he is more physical and ‘real’ than this world. That’s why we can’t see him, but also why he is more present and more powerfully real in the world than if we could see him.
There, I suppose I have confused everyone totally, and perhaps I’ve even strayed into heresy, who knows. If I have offended anyone or strayed off track simply say I am being speculative….