The years following publication of the Principia Mathematica in 1687 saw a gradual but definite change in the character and spirit of the European scientific movement. Newton's masterpiece showed for a fact that the ‘new philosophy’ could solve the most imposing of problems. No longer was it necessary, as in the heroic days of Bacon, Galileo and Descartes, to convince contemporaries by argument of the power of experimental and mathematical science. Scientific deeds had spoken for themselves. At the same time the Principia brought to a conclusion the great cosmological debate opened by Copernicus, and established mechanics as a model for all the sciences. With these developments, a period of adventure in ideas and organization gave way to one of systematization, fact-collecting and the diffusion of scientific ideas. Science became for a time distinctly less original. In 1698, Gottfried Wilhelm Leibniz (1646–1716) and the aged John Wallis (1616–1703), discussing in the Philosophical Transactions of the Royal Society ‘the cause of the present languid state of Philosophy’, found that among their younger contemporaries ‘Nature nowadays has not so many diligent Observers’. Two years later the Council of the Royal Society regretfully recorded that neglect and opposition had thwarted their plan to produce a series of useful inventions. Yet at this very time the influence of science was spreading as never before. A new profession had grown up. Scientific societies of high technical standards were soon to multiply, governments investing in science with the expectation of a profitable return. An expanding scientific journalism was spreading a new philosophy among a wide lay public.