Popular books on mathematics tend to cover the same ground, highlighting a few easily explicated examples (Fibonaccis rabbits, Pascals triangle, Hilberts hotel) rather than trying to illuminate the whole landscape. Elwes has set out instead to create a concise laymans encyclopedia of mathematics, addressing each topic in clear language and including extensive cross-references to situate it in the larger picture. The result is an accessible, absorbing introduction to the discipline, touching on number theory, geometry, algebra, discrete math, analysis, logic, metamathematics, probability, mathematical physics, and some recreational math. The whole can be read straight through or consulted as a reference. One of the best nonmathematical surveys of math that Ive seen.