Samuel Johnson wrote: "We cease to wonder at what we understand". To put it another way, all understanding, in the sense of knowledge, definition, measurement, stops short of what is truly wonderful. When we wonder, when we're struck by astonishment and delight at some new marvel, we realise that we're out of our depth, and yet that we are being kept afloat. There is nothing for us to do except wonder. And this wonder has its origin in God, who is beyond our understanding.
For me, the Resurrection of Jesus Christ, and all the possibilities it discloses, are an endless source of wonder - as real as unexpected kindness or the flight of a swallow, and just as impossible to understand.