The Fourth Cut

I own four Swiss Army knives.
     The first I bought when I hadn’t much money but really wanted a knife that could cut down a tree.
     The second—a Christmas present from my sister’s new boyfriend—fit on a keychain and, as he said, was handy for clipping your nails when you had nothing else to do.
     The third was a parting gift from my first job, the largest model available, and so should’ve been my last; but for the fourth, which I got from my girlfriend and thought . . . why don’t you know I already have three of these things?