world around us is real and objective. It is concrete and particular. It has a determinate quality, shape, and texture. And it is full of “impenetrable mysteries.” This world of sights and sounds and smells, “this astonishing cataract of bears, babies, and bananas, this immoderate deluge of atoms, orchids, oranges, cancers, canaries, fleas, gases, tornadoes and toads”4—this is what Lewis calls nature. So, to begin where you are means that you begin here, in the present location. Second, the exhortation