Jack is a guest in Harry's home. While there, he goes into the library and picks up a music box that is part of Harry's collection. Jack overwinds the stem and it breaks. Hoping Harry won't notice, Jack takes the music box for repair to a jeweler who sells similar ones. The jeweler fixes it, but forgets to tag it and an unsuspecting clerk sells it to Robert. Jack is frantic. Can Harry get the music box from Robert?
(A) No, the jeweler gives good title to a bona fide purchaser for value
B) No, the jeweler was not a merchant with regard to the music box
C) Yes, Robert was not a buyer in the ordinary course of business
D) Yes, Robert has assumed only Jack's title, which is no title at all

Jack never owned the music box, he just took it to the repair shop. No title was ever passed form Harry to Jack and Jack didn't even have the intention to take the music box for himself.

In this case, Jack messed up, and he cannot get the music box back, but once he tells Harry, then he can claim it back. Even if Robert was a buyer in good faith, it doesn't matter because he cannot purchase something from someone that doesn't own it.