I've Been Living A Double Knife

On Monday, my three oldest1 sons were playing in the master bedroom closet. This mostly involved trying on my wife's shoes, which sit on a shelf beneath all of my hanging clothes. After this had gone on for a while, the nine-year-old walked into my office. He handed me a penknife and said "I found this in one of mom's shoes." I was about to casually thank him and put it away when I noticed that the blade had a gray patina2 to it. "Wait a minute," I said. "This is the one I replaced because I thought I'd lost it! The replacement has a shiny blade!" I then started hunting for the replacement so I could show him the difference. I searched my nightstand drawer, my "watch & knife box" in the office, my backpack, my desk, and various pant pockets to no avail. "Well," I said. "I guess I've lost the new one now." About an hour later, my nine-year-old walked back into my office. He handed me a penknife and said "I found this while I was cleaning toys out of under the couch." This time, the…