Say I were to tell you "I have a large treasure chest full of gold doubloons" and you were to say "Really, let me see it?", so we went to my house to look at my chest.
We enter my living room, where there is a fireplace with a mantel. I say "Look, it's right on top of the mantel", but there are only picture frames.
You approach the fireplace confused. "Where is it?" you finally ask.
"Don't you see, right here." I say, walking towards the fireplace and picking up one of the picture frames atop the mantel.
"Isn't it beautiful, my chest full of gold?" I say, handing the picture to you.
You look at the image in the frame. It is not just a picture, but a picture of a picture of a chest full of gold.
So, clearly, I am out of my mind.
With material objects, it's quite obvious to any sane person when they truly have them or not. Even if it is not obvious, it will be obvious to some other sane person.
With immaterial objects, like opinions, it is not so obvious. Many people's "opinions" on a subject are truly images of images of an opinion. This is not so easily felt, nor can it be easily identified by the person who is being told the opinion is legitimate.
You should be careful to make sure when holding a belief "Do I have this, or do I have an image?"