Ok, so in the ep" i remember you" there was a pic that marceline showed to ice king after the GMW. And guess what simon was holding??? The Enchiridion! How did he get it?( if you look at the top, it says"Simon Petrivok Unearths Ancient Treasure",so he probs discovered it) so It is protected by manish man in the mountain thing, (and simon dose'nt look like a hero) so it is strange.
I saw the pic when watching i remember you, and i thought he was just holding a normal book( you could also see betty in the car that he took the picture on, but that does'nt matter)
Here is the pic: