"So what does this one do?" you asked as you showed a watch to the Wizard. You watched as his eyes lit up.
"Ah, the Silver Watch. It has been a long time since this was used. It allows you to live the life of another in a different point in time, both past and future." He paused for a moment. "And it is completely safe, of course."
"But what is with this warning," you said, pointing to the shelf.
"Oh, that. That was a warning about making paradoxes and such. I fixed that up, but it had the side-effect of occasionally causing errors."
Now this was worrying. "What kind of errors?"
"Nothing to concern yourself about. Just little hiccups here and there. Nothing dangerous at all."
Your interest won over your caution, and you bought the watch. Now, what to do with it?