So I am running this morning at a wonderful park where I live. It’s a great run, through a lot of shade, with breaks of sunlight and the intermittent odd obstacle course element thrown in- mini lakes, occasional mud fields and a bridge or two to run under. As I was running, through the bright sunshine, the underpass loomed ahead, just a dark space, impossible to discern anything. Yet, in a couple of seconds, upon entering the darkness, my eyes had adjusted and it was easy to make out the odd array of tree fragments, swampy flowers and pieces of what appears to be prehistoric rock. But then my strides take me out again, into the blazing light, and all I can think about is how great it is to have eyes that work-those rods and cones really have delivered the goods for me.