Natural contemplation requires us to use our reason and reflection on creation to learn how to use God's creatures for His glory. At the liturgy, when we bring before the altar the gifts of bread and wine - these signs of human culture - they are offered by us, representatives of the world, and indeed the whole creation, and God takes these and responds by transforming them into the Body and Blood of His Son. This transaction is a sign of our common priesthood. We are the high priests of creation - all of us together, baptized Christians, make the world more rational, more hospitable, more gracious, more beautiful...bit by bit, through our cooperation with God's grace, the cosmos is sanctified.