THE RENAISSANCE 113 



back to the hills as rain. It seems that Leonardo 

 understood the circulation of the blood a hundred 

 years or more before it was rediscovered and Harvey 

 gave the knowledge to the world. Once more his art 

 led him to a scientific problem, in the structure and 

 mode of action of the eye. He made a model of its 

 optical parts, and showed how an image was formed 

 on the retina. He ignores the view, still held by his 

 contemporaries, that the eye throws out rays which 

 touch the object it wishes to examine. 



He dismisses scornfully the follies of alchemy, 

 astrology and necromancy ; for him nature is orderly, 

 non-magical, subject to immutable necessity. 



But we have said enough to illustrate Leonardo 

 da Vinci's position in the history of scientific thought. 

 Had he published his work, science must have ad- 

 vanced by one step to the place it reached at least a 

 century later. It is idle to speculate on the influence 

 of such a change on the story of the human mind, 

 and the evolution of human society. It is safe to 

 say that both would have been modified profoundly. 



But, though Leonardo never carried out his oft 

 referred to project of writing books on different 

 branches of his labours, his personal influence was 

 clearly immense. The friend of princes, he knew 

 also all the men of learning and affairs of his time. 

 His ideas were not all sterile, but some fell on the 

 good ground which, years later, gave birth to a new 

 growth of scientific achievement, springing from the 

 seed scattered by Leonardo and his disciples. If we 

 had to choose one figure to stand for all time as the 

 incarnation of the true spirit of the Renaissance, we 

 should point to the majestic form of Leonardo da Vinci. 



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