I have a different, though related, puzzlement:

I don't buy large numbers of pens. In fact I seldom buy any. But I find that I have a bunch of pens around--at the computer, in my pocket, on the passthrough from the kitchen to the breakfast nook. But this population is continually changing: As soon as I realize that the one I just picked up is really comfortable, and/or writes very smoothly, and/or has a good-looking writing line, it will disappear, probably to the same place as the pens from Arthur_itus' house. But more mysteriously will appear.

Go figure.

Dave Oesterreich