Flatland: A Romance of Many Dimensions is a delightful experimental novella, a fictional exploration of dimensions and perspectives beginning in a two-dimensional world, Flatland, populated by two-dimensional geometrical shapes. The novella is narrated by one of Flatland's residents, A. Square (when the novella was first published in 1884, it was published under the pseudonym, "A. Square").
The first half of the novella is a description of this two-dimensional world, such as how it looks and how the figures move, spiced up with a clever dissection of Flatland's social hierarchy, which is dictated by the number of sides one has. Square's subsequent explorations lead him to Lineland (a one-dimensional world), Pointland (no dimensions), and then to Spaceland with its three dimensions.
