All of Scripture is pointing back to the creation story, and all of Scripture is pointing ahead to Christ. In creation, God works for 6 days, and all things are done, so God rests and enjoys communion with God's creation. Things are complete. In the same way, the Lord's glory covers the mountain for 6 days, creating the atmosphere where God can then commune with Moses on the mountain, so that the people of God can be re-created here at Mt. Sinai.
This process takes forty days, the same number of days that Christ goes into the wilderness to prepare for his public ministry, the same number of years the Israelites will dwell in the wilderness before they enter the Promised Land.
Scripture is a spiral, returning to the same point over and over, and yet the people are different, having grown, having learned about God, traveling forward, ever closer to the fullness of the Kingdom of God.
We are the same way -- we grow every year as we return to the same points -- to Lent, to Advent, to Easter, to Christmas, to Pentecost. We change, we grow, and so we are not the same, and every year, we are closer to the fullness of the Kingdom of God. The more we learn about our past, about our history, the better we understand the future, and the people we are called to be. We don't leave the past behind, but grow out of it, into a future where the past is redeemed and we are restored to right relationship with God and one another.
