An abstract and philosophical discussion of representation, primarily of the political kind although the author occasionally goes far beyond the bounds of politics to illustrate the concept. These excursions sometimes seemed a bit far-fetched to me, but even so this is a very good book. If you want to philosophize about the nature of political representation this book is an indispensable starting point. The book is over 40 years old now but has retained its value and it is also a very useful bibliographical source for early 20th century works in democratic theory.