that paintings might have hidden meanings that only the artist saw??????

Yea, i think they do. I think the artist might be trying to show an image completely different than what people actually see.

Many times they do. Other times there are meanings placed onto the paintings after the fact (by others) that the artist never intended.

If the artist comes out and says that wasn't his intent at all, they'll say the artist clearly doesn't know what he's talking about, and that he obviously DID load that painting up with that particular meaning, if only subconsciously.

And if the artist has been dead for ten years, or a hundred, or five hundred, everyone and his brother thinks they're an expert on the artist's intentions.

If Leonardo were able to peek into our plane of existence from his, and see the fuss being made about "the Last supper", I think he'd probably say "WTF?"