I have taken up the habit of walking a prescribed path along the edges of the yard. This walking is different from the other kinds of walking I do - the brisk striding to the highway and back that increases my heart rate and makes me feel I'm doing at least a little something toward maintaining my good health; the slow and purposeless ambling through the woods, looking for nothing in particular but hoping to stumble upon something astonishing. This walking, this perimeter walking, is not slow or fast.