Karl Popper 
Open Society and its Enemies [PDF ebook] 

Written in political exile in New Zealand during the Second World War and published in two volumes in 1945, The Open Society and its Enemies was hailed by Bertrand Russell as a ‘vigorous and profound defence of democracy’. This legendary attack on the philosophies of Plato, Hegel and Marx prophesied the collapse of communism in Eastern Europe and exposed the fatal flaws of socially engineered political systems. It remains highly readable, erudite and lucid and as essential reading today as on publication in 1945. It is available here in a special centenary single-volume edition.