Many books and papers have helped me as well as those already listed. The best students’ guide to the work is Nikolas Pappas, Guidebook to Plato and the Republic (London, Routledge, 1995). Julia Annas, An Introduction to Plato’s Republic (Oxford, Oxford University Press, 1981), is a classic modern discussion combining philosophical depth with readability to a remarkable degree. Sir Karl Popper, The Open Society and its Enemies (London, Routledge, Kegan and Paul, 1945), vol. I, Plato, is a polemical masterpiece, and as one-sided as that implies. Melissa Lane’s treatment of the modern reception of Plato in Plato’s Progeny (London, Duckworth, 2001), often left me worried whether there was anything left to say. An older classic, Paul Shorey’s Platonism Ancient and Modern (Berkeley, University of California Press, 1938), is a wonderfully urbane and learned ramble through historical byways.