This may be considered a Science Fiction book, but it is (IMO) very important to anyone who wants to free themselves of "common" belief, and try to understand higher dimensions. Your narrator is a square (the actual geometric shape). The first Part of the book deals with life in "Flatland". The inhabitants of Flatland are two-dimensional, and believe that this is all there is to the Universe. Nature (along with certain laws and regulations) is set a certain way, in Flatland, so that the inhabitants can go about there normal lives, without need of another dimension. In the second Part, your narrator (the Square) has a dream about Lineland, a place where all of the people are lines, and move along one dimension only. They only see each other as points (much like inhabitants of Flatland only see each other as lines), and believe that there is nothing more to the Universe than the "line". When the Square tries to explain the second dimension to the Kind of lineland, the King dismisses him as a fool (among other things). Later, as the second Part continues, the Square is visited by a Sphere. The Sphere tries to get the Square to visualize the third dimension, but the Square just couldn't do it. Finally, once the Square gets to understand the third dimension, he (the Square) tries to get the Sphere to imagine dimensions higher than the third one. I recommend this book to everyone, but particularly those with an interest in knowing the unknowable (like me).