Given the repeated failures and frustrations of workers' revolutions and movements, Marx also sought to understand capitalism and spent a great deal of time in the reading room of the British Museum studying and reflecting on the works of political economists and on economic data. By 1857, Marx had accumulated over 800 pages of notes and short essays on capital, landed property, wage labour, the state, and foreign trade, and the world market, though this work did not appear in print until 1939 under the title 'Outlines of the Critique of Political Economy'.