I generally carry three to four books with me whenever I travel. On my recent trip to Paris, I had the pleasure of working my way through "The Dispossessed" by Ursula Leguin.
In many works of science fiction, time itself is the principal actor. The future provides evidence of the progress of mankind, allowing man (or the equivalent) to explore the limits of consciousness. In many works, the chief evidence of this progress comes in the form of a series of technologies. In "The Dispossessed", the chief developments are cultural and intellectual. Annares, the anarchist moon on which our main character begins the story, is rendered as fully as if it were a separate character. Citizens alternate between pursuing their individual talents (if they have any) and taking whatever work needs to be done. In a world where material goods, housing, and even partners and children are freely interchanged, peer approval is one of the only forms of riches, and peer disapproval the chief punishment.
The main character travels from this world to the neighboring (and dominant) Urras, a materialist society which includes women and servants among the things that can be possessed. The contrast between the two cultures with regards to class, gender, and intellectual achievement helps to illuminate the ideas on which both are based, and provides food for thought.
A good book, and well worth reading.