Popper’s three-part postscript to his first published book, The Logic of Scientific Discovery (1936), represents one of the major works on determinism and indeterminism. Although the culmination of Popper’s work in the philosophy of physics (reaching its peak in the second volume, The Open Universe) the Postscript took almost three decades to be published. Originally intended as appendices to a later edition of The Logic of Scientific Discovery, the project grew into a fully-fledged work which actually exceeded the length of the original work. In 1956-7 The Postscript was all set to be published and already existed in the form of galley proofs but because of his deteriorating eyesight Popper was never able to proof-read the galleys and the whole project remained on hold for 25 years.