Shaving in the morning, something was strange. John used to have blue eyes; now they were brown.

Then he found, whereas he had always been left-handed, his left hand was less adept at brushing his teeth than his right.

Otherwise, as far as John could tell, he still looked the same, and he still thought his name was John.

The next morning, John brushed his teeth and looked in the mirror again. He saw that he remained a brown-eyed right-hander. If a foreign spirit or something else had entered into his head and changed him, for what purpose yet undisclosed would it have troubled itself?

John was 69 and he had thought he was too old to change, although it obviously wasn’t true. He had changed.

John decided to become a landscape painter. He had never painted landscapes or anything else before, but he realized how easy and nice it would be to buy the paints, brushes, and canvases, and then to go outside to paint landscapes. It took a while, but, eventually, John became a successful landscape painter.

Had John become a landscape painter because of the changes he had first observed when shaving, or would he have become a landscape painter anyway?

John remembered the axe whose handle had to be replaced, then the axehead chipped so its owner, Pete, replaced it, then the thong that tied to axehead to the handle had to be replaced. Pete replaced each part with an identical part. Did he own the same axe?

Then suppose that Pete’s friend Fred did not have an axe. Pete removed the axehead from his axe and gave it to Fred, replacing it with his old, chipped axehead. Fred found his own handle and thong, so now each had an axe. Did Fred have the axe that used to be Pete’s, or did Pete have it?

John’s friend Paul got cataract surgery and titanium hips. Another friend, Petunia, had a brain aneurysm. Whereas she had been cantankerous before, after the aneurysm her disposition was sweet. These were only two cases out of many.

As far as he could tell, John still had the same eyeballs and the same hands. So what if he behaved differently?