"...taking their soul".

I think this is an interesting quote, and true in some ways.  Not literally.  But the fact is that in a picture you do portray people, and that may possible show some of who they really are, or in fact show their soul.  If you're not honest about the goal of your photo or why you're taking a picture of that person then if you mis-portray them it is somewhat unfair to them.  It's wrong to use images of a person without properly explaining what they're being used for.