NEWTON was hardly an unknown man in philosophic circles before 1687. The very extent to which he had made his capacity in physics and mathematics known had functioned in the early 1680s to destroy his attempt to reconstruct an isolation in which he might pursue his own interests in his own way. Nevertheless, nothing had prepared the world of natural philosophy for the Principia. The growing astonishment of Edmond Halley as he read successive versions of the work repeated itself innumerable times in single installments. Almost from the moment of its publication, even those who refused to accept its central concept of action at a distance recognized the Principia as an epoch-making book. A turning point for Newton, who, after twenty years of abandoned investigations, had finally followed an undertaking to completion, the Principia also became a turning point for natural philosophy. It was impossible that Newton's life could return to its former course.

Rumors of the coming masterpiece had flowed through Britain during the first half of 1687. In Scotland, David Gregory held up the publication of a method of quadratures until he saw if Newton printed his method in the Principia. It was a judicious precaution on Gregory's part, since he had only recently plagiarized the method from the notes that John Craig had brought home from Cambridge in 1685. When the young Swiss mathematician, Nicolas Fatio de Duillier, arrived in London in the spring, he found intellectual circles aflutter with expectation of the book which would, he was assured, remodel natural philosophy.