Once, the great British philosopher Ludwig Wittgenstein was having a conversation with a friend.
Wittgenstein : Tell me, why do people always say that it was natural for men to assume that the sun went around the earth rather than the earth was rotating?
Friend : Well, obviously, because it just looks as if the sun is going around the earth.
Wittgenstein : Well, what do you think it would look like if the earth was rotating?
This conversation, just like the Upside Down Map, always managed to give me quite an eerie feeling every time I think about it. After all, we know that the concepts of 'up' and 'down' doesn't have meanings when it comes to earth, yet the said map kind of makes me feel strange whenever I look at it. Similarly, while it is perfectly reasonable to assume that sun goes around the earth because it looks that way, we never stop to think of the other possibility, that it would look exactly the same if the earth rotated. In fact, that is exactly what it does, only nobody bothered to think of it that way for a very very long time.
This is why I have a framed photo of the said map in my room, and also why I will never forget the above conversation. Those always keep reminding me that things are not always what they seem and that after all, perception is everything.