134 PROGRESS OF SCIENCE IN THE CENTURY. 



defining more clearly the direction in which Newton's 

 views require to be extended or modified." * 



As to the import of Newton's work, three points 

 may be distinguished. 



First, it affords what is probably the most striking 

 instance of the application of scientific method, and 

 part of its influence has been that of an illustrious 

 example. It signalised once for all the contrast 

 between metaphysical contemplation and scientific 

 study. 



Secondly, in the so-called law of gravitation, which 

 describes " how every particle of matter in the uni- 

 verse is altering its motion with reference to every 

 other particle," Newton not only enlarged the horizon 

 of physics, but gave the world perhaps its finest illus- 

 tration of a focalising "thought-economising" for- 

 mula, whose universality and accuracy seem alike 

 indisputable. Here the science passed beyond ob- 

 servation and description to the recognition of a uni- 

 fying idea. 



Thirdly, in his laws of motion and other principles 

 Newton gave a marvellous if still imperfect pre- 

 cision to the concepts of force, matter, and the like 

 with which the physicist works. Some would say 

 with Prof. Ernst Mach f that Newton " completed 

 the enunciation of the principles of mechanics," or 

 with Thomson and Tait that "every attempt to 

 supersede them has ended in utter failure " ; while 

 others would rather say with Karl Pearson that the 

 progress of two centuries has given good reason for 

 trying to modify and restate the Leges Motus, es- 

 pecially in the direction of purifying them, if it be 



J. T. Merz. History of European Thought, I., p. 817. 

 fj/ectanifc in ihrfr*RntwicMung, 3d ed., 1889, trans. 

 Chicago, by J. T. McCormack, 1893. 



