The Grand Canyon: natural wonder of the world. I’ve been there a few times now and the sight of it never fails to stop me. Stop me dead in my tracks, overcome by its immeasurable size and layered, many-coloured, beauty. It seems to me that I even stop breathing because there is simply no breath left for the expletives of awe and joy that fill me but, uncharacteristically, never leave my body. Previously, however, I had never walked down into the canyon, and it was this that was the object of my being there two weeks ago. To look at the Grand Canyon is not just to see the world’s…