In the mid-nineteenth century the pursuit of scientific knowledge at last attained true autonomy and independence. Emerging as a consistent discipline with experiment and observation as its sanctions and mathematics as its logic, science extended its province far into space, and brought millions of years within the scope of its pronouncements. Emancipated from the limitations imposed by formal reasoning and dogmatic theology, an unquestionable force of certainty was claimed for scientific truths such as had never before been granted to any products of the intellect; and though only a small part of the swift advance in material civilisation that was made in this period can be directly attributed to contemporary progress in science, vast accretions of potential power were being built up. The formative period of modern science in which its character, its methods and its problems were established may be said to have ended about 1830; the modern age, with the technical ascendancy of science, to have begun about 1870. The interval is both classical, in that it contains the fulfilment of much that had been originated earlier, and transitional, because the beginning of recent science lies within it. Without abrupt discontinuity there was a remodelling of activity, a displacement of some guiding concepts of scientific thought by others. A single individual, like James Clerk Maxwell, might in one investigation add a coping-stone to the fabric of Newtonian celestial mechanics, while in another he helped to lay the foundations of the new theoretical physics. The doctrine of universal gravitation received its fullest vindication in 1845–6 from the discovery of the planet Neptune in accordance with theoretical predictions, when Newton's optical theories had already been shaken by the newer theory of wave-motion.