Yesterday, taking Mabel to Prospect Park, and then meandering through Park Slope, I must have walked ten miles. And so today, and last night too, my poor arthritic knee is in sad shape. I can actually feel the two bones scraping together; years ago, when I had surgery to fix the knee, they discovered that some cartilage was damaged and had to be removed. My doctor told me about a new procedure in which some kind of foam is injected into the joint, to replace the missing cartilage, thus protecting the joints and cushioning them. I hope my medical insurance will pay for it.