I admit to not understand how the trick was done when I read the beginning of the article. I of course realized it was a trick, it's just that it didn't occur to me how it was done. Then I continued reading and of course the resolution was obvious, but only after I had read it. Now, of course, I can't unlearn it. And the reason I didn't get it was exactly the point put forward in the article: The title of this thread.