Anyone who liked "Flatland", will love "Flatterland". It's a continuation of the story of "Flatland", from the PoV of A. Square's great-great-granddaughter: Vicki Line. Instead of "The Sphere", Vicki's guide is called "Space Hopper", and if you thought "The Sphere" heightened A. Square's awareness of mathematical reality, just wait 'til you see where the Space Hopper takes Vicki! They go all over the "Mathiverse", visiting a "Fractal Forest", having a "Topological Teaparty", and on and on, through insane-seeming realities that actually have mathematical meaning! In the spirit of Lewis Carrol and Edwin Abbott, Ian Stewart takes the layperson through a huge array of complex mathematical concepts, but makes them easy to understand (even, almost, conceptualize (for example, it seems obvious to state that an extra dimension would allow one to untie a knot in a unique way, right? Well, Space Hopper actually helps you conceptualize it.). Such things as fractional dimensions, an infinite number of dimensions, hypersphapes intersecting our plane, time, topology, etc, are made fun and interesting without ever really using any math! It's also hilarious! Stewart writes with engrossing humor and intense interest in each different point of VUE (read the book, and you'll know what I mean). I highly recommend it.