While they were all amazed at his every deed, Jesus said to his disciples, "Pay attention to what I am telling you. The Son of Man is to be handed over to men." But they did not understand this saying; its meaning was hidden from them so that they should not understand it, and they were afraid to ask him about this saying. Luke 9:43-45
I've always wondered why Jesus refers himself as the "Son of Man" and not the "Son of God." Yet there were many times when one of the apostle's would refer to him as the Messiah, the Chosen One, and the Son of God. But in today's reading we read about Jesus asking them to pay attention to what he is telling them.
I am often reminded of the many times when listening intently to someone speak, only to find I didn't understand what was said until a few minutes later or much later than that. It has nothing to do with a sluggish mind as we tend to think, but God's purpose in keeping it hidden at the time, until we need it. And when that happens it's as if a light goes off in our minds, a dawning of reasoning. What was said to us just happened to become clear. I think about the apostles now and what Jesus asked of them, and them wanting to question him. It will come to them when the Holy Spirit will reveal in time what the meaning is about.
The apostles are not dumb, just like we are not either when things are hidden from us, it is part of God's plan and the Holy Spirit's, in our understanding his hand in all of it.
When I first wrote the paragraph at the beginning I wondered about why Jesus calls himself the Son of Man, and understanding his purpose was not to reveal who he truly was but for us to see with eyes of faith who he really is. We are made in God's image so in truth he is the Son of Man, but he is so very much the Son of God.
He foretells his pending captivity to the apostles, the handing over to us for the sake of our salvation. He was trying to prepare them for what is to come.