130 DISCOVERY CH. 



thoroughly the laws relating to the movement of water 

 and hydraulics generally, and anticipated many of the 

 theories for which credit is often given to men of science 

 who lived many years after him. Hallam, in his Intro- 

 duction to the Literature of Europe, says that the 

 discoveries which made the names of Galileo, Kepler 

 and others famous, the system of Copernicus, and the 

 theories of modern geologists, were anticipated by 

 Leonardo within the compass of a few pages ; not 

 perhaps in the most precise language, or in the most 

 conclusive reasoning, but so as to strike us with some- 

 thing like the awe of preternatural knowledge. In his 

 work as an engineer he followed truly scientific methods. 

 " Those," he said, " who are infatuated by practice 

 without science, are like the navigator who sails a ship 

 without helm and compass ; he never knows with 

 certainty whither he goes. Practice must always be 

 built upon theory. Study science first, then follow the 

 practice which is born of science." 



Bernard Palissy, the potter who sacrificed everything, 

 even the furniture of his cottage, in the production of a 

 glaze for earthenware, was also one of the earliest 

 followers of the experimental method of studying other 

 aspects of Nature. His life extended over nearly the 

 whole of the sixteenth century, and his contributions 

 to agriculture, chemistry, mineralogy and geology dis- 

 turbed the schoolmen and provided a new foundation 

 for science. He was the first to give a true explana- 

 tion of the origin of springs, and like Leonardo da 

 Vinci, he understood that fossils represented past 

 forms of life and were not freaks of Nature or relics of 

 the world before Noah's flood. Buffon said of him, 

 about a century and a half later, " a simple potter of 

 the end of the sixteenth century was the first to dare, 



