The Communist Manifesto (Little Black Classics #20) - Friedrich Engels, Karl Marx
A seminal work, which offers an interesting, if dated, critique of capitalism and an alternative way of perceiving the world's dominant system of social organization. Certainly the thoughts expressed by Marx lays bare the assumptions which accompany our embrace of capitalism, but its longevity may owe much to the absence of a workable alternative to date (the subsequent attempts at the implementation of communism being largely discredited).