From game theory to the Gambler's ruin this book has classical mathematics well explained. The section on permutations and multinomials is still a valuable reference after all these years! But it is the application of permutation groups to island marriage laws that make this book a mathematical classic! How close a relative can you marry without endangering the gene pool while maximizing the number of people in your tribe that you can marry... a practical problem set to a primitive culture produced mathematical solutions!