By Edwin A. Abbott, 1884, 144 pages, full text, amazon
As we can read in the introduction to Flatland:
Here is a stirring avdenture in pure mathematics, a fantasy of strange spaces peopled by geometrical figures; geometrical figures that think and speak and have all too human emotions. This is no trifling tale of science fiction … it is written with subtle artistry. Start it and you will fall under its spell.
Even though this book was written more than hundred years ago, it could have been written yesterday and you would never know. Well, maybe you would, because an author writing today would probably weigh words more when talking about women and minorities. In the world of Flatland, inhabited by squares, circles and other 2D geometrical figures, women are straight lines (both dangerous and inferior to anybody else) and regularity is highly priced (anybody irregular is either destroyed or lives at the lower end of society). What might have been a sad irony 100 years ago in Britain would most likely be a misunderstood statement in today’s America.
Apart from that, this short book is a delight. At the beginning you learn what is it like to live in this flat world and then you follow a square in his adventure of discovering other dimensions. As you see him struggle with accepting the third dimension, you cannot help drawing parallels and thinking about the fourth one.
Even though this book is filled with words like geometry, dimension and equilateral, it is still highly readable and non-mathematicians can enjoy it at least as much as mathematicians can, maybe even more. If you would like a short preview, here is a trailer from the movie based on this story: