The concept of the transformation of scientific ideas took its present form during the spring and summer of 1965, while I was contemplating the factors in scientific revolutions, a feature of the Wiles Lectures, on which this book is based. This concept was put to the test in the spring of 1966, while I wrote the first of the lectures, on the history of inertia (of which a portion is embodied in Ch. 4), a topic which notably displays the complexities of ways in which a scientist uses the ideas (and the names of ideas) of a predecessor or contemporary. As the reader may see for himself in this sample, the very facts of this history stridently declare that in each stage of the development of the concept and law of inertia, a scientist altered and adapted something that he had encountered in his reading and studying of the writings of a contemporary or predecessor.

The Wiles Lectures were delivered at Queen's University, Belfast, in May 1966. In the following autumn the doctrine of transformation was expounded in a privately distributed edition of the first two of the lectures, bearing the general title, Isaac Newton: The Creative Scientific Mind at Work. A revised and expanded version of the chapter on the history of inertia was presented for discussion at a symposium held in Prague on 25–29 September 1967, on the occasion of the three-hundredth anniversary of the death of Joannes Marcus Marci of Cronland, of which the general theme was ‘La révolution scientifique du 17e siècle et les sciences mathématiques et physiques’.