Brought to you by Penguin.'Man was born free, and everywhere he is in chains.'These are the famous opening words of a treatise that has stirred vigorous debate ever since its first publication in 1762. Rejecting the view that anyone has a natural right to wield authority over others, Rousseau argues instead for a pact, or 'social contract', that should exist between all the citizens of a state and that should be the source of sovereign power. From this fund...