This is probably my second favourite Discworld novel so far (after Small Gods). It is wonderful to see Terry Pratchett's evolution both as a writer and a philosopher. The characters and world are becoming more complex and well-realized and real. Moving from his earlier books which exist mostly to poke fun at fantasy concepts to these books which are clearly allegories for the real world, it is difficult to compare them. The themes of this book centre around racism, sexism, civic duty, and the sanctity of life. Pratchett's exploration of these themes is sometimes problematic, however it is far beyond his earlier forays into these territories. A brilliant book.