Galileo's work represents something of a historical singularity: he was able to create the new science of motion—classical mechanics, with its solid mathematical foundation—almost single-handedly, breaking with his forebears and little influenced by his contemporaries, Maurice Clavelin's book assesses this singularity by carefully analyzing the concepts and methods that Galileo used in the development of his new science.
Stillman Drake, who is among the foremost authorities on Galileo, has stated that “I have seldom read a book of this kind with as much pleasure and interest as I read this one. There is no question in my mind that it is the most significant contribution in its specific area since 1939, when Alexandre Koyré published his Etudes Galiléennes. It is by no means a mere summary of the results of other scholars.... The author has made his own analysis of the entire field described by the title of the book. The result is that of a fresh breeze through a room that has not been aired out in a long time.”
Reviewing the French edition of the book in Isis, Professor Drake points out the significant differences in outlook between Koyré and Clavelin: “Clavelin brings into focus some important considerations respecting Galileo's own procedures and achievements, and those of his forerunners, that call for substantial revision of Koyré's conclusions. Without the slightest trace of a polemic tone, he finds himself compelled to reject the Platonist interpretation of Galileo's science and to reinterpret substantially the influence of medieval writings on its creation.” Further, the merit of Clavelin's work “lies not in the denial of Aristotelian and medieval influence on Galileo's mind and work... but in the exact analysis of those influences.... For the perception of the respect in which Galileo's case is unique, Clavelin has established the most fruitful viewpoint from which Galileo's case may be seen to resemble those of his forebears and his successors.”
The book opens with a review of the traditional theory of motion as it stood in Galileo's time: although it was based on Aristotelian doctrine, Clavelin traces important amendments to this doctrine to fourteenth-century thinkers in Oxford and Paris. The book goes on to analyze Galileo's own science of motion, first on the cosmological plane (in particular, his justification of the Copernican theory), then on the plane of “rational” mechanics (the geometrized theory of the motion of heavy bodies). The final chapter, “Reason and Reality,” is devoted to Galileo's method and explanatory ideal.