One of the first inexplicable finds by archaeologists traveling to the future is the blue
knife made of no known material brought back by Walter Toynbee who promptly dies, leaving it
to his grandson to explain the origin of the knife.
I knew grandfather. He would go as far as his machine could take him. I had duplicated
that. He would look around him for a promising site, get out his tools, and pitch in.
Well, I could do that, too.