What does “an apple of….” mean? I don’t think that it is about an apple as a fruit! Please, help!
Actually I suppose it is about an apple. Do you know Wilhelm Tell? His legend has it that he was a fighter for freedom in Switzerland's history. I don't recall all the details, but there's a story about him being forced to shoot an apple from the head of his son with his crossbow, which he managed to do. I suppose this is in reference to that story.

Robin