Hmmm...the professor made good points and made Hannah think that maybe this wasn't a wizarding city afterall. I mean sure the whole muggles not knowing about it and most believed it to not exist sounds like something that might be magical, but this Plato dude was obviously a muggle. This had to be why Hannah did not know about him.

"Professor I don't think Plato is a wizard because we would know about him in the wizarding world and the muggles would not know about him at all." Did that even make sense? "I think the muggles know too much about him for him to be a wizard." About the city being under water, Hannah didn't know how to go about that. Maybe the muggles didn't really care about what this fool was talking about and didn't care to go look for it.