I've always been fascinated by what people could mean when they say this. I believe many people mean 'the part of me that thinks' or 'the part of me that makes decisions' when they say souls... but what could it mean for that part of you to be stolen? An inability to think or make decisions? Or something about vanity and getting wrapped up in images of yourself? Or fascination with a device that looks like a big eyeball?
It'd really be great to know what people mean when they say that.
Nope, I think it stems from the idea that a representation of someone=someone.
I remember reading a book from an american guy who recalled what happened to him when he was travelling in another country. He suddenly realized that he had lost his wallet (it was stolen) and it contained pictures of his children inside. Those were just simple pictures and he could have made copies once coming back home, but instead he wandered in the dangerous quarters of the city to try to find back the pictures from his wallet. He could have been robbed or worse, but he explained he was not aware of those risks at that time because the only thing he was thinking about was that "I have to find my kids back". He made a clear association between the pictures and the persons.
He then said he could understand the saying regarding pictures and souls, since he went through this experience.