THE PATH OF EVOLUTION 



the answers to questions that reason and experiment 

 answered otherwise, nor could he let the authority of 

 Aristotle intervene when his own experience was a 

 better teacher. He boldly defended his own views 

 and combated those of others, so that he acquired the 

 reputation of being obstinate and contradictory. 



Before he was twenty years old he made the first 

 of his great discoveries by observing the swinging 

 of the large lamp suspended from the vaulted roof 

 of the church. He noticed that its oscillations were 

 made in equal times, whatever might be their length. 

 He remembered the fact and made use of it fifty 

 years later in the construction of a clock for astro- 

 nomical observations. As yet Galileo knew little 

 about mathematics. His father feared to let him 

 study therein, lest it would interfere with his zeal for 

 that of medicine. At last, after long persuasion, his 

 father yielded his consent. From that time everything 

 was forsaken for the new study. He delighted in the 

 demonstrations that put him in possession of certain 

 and unquestionable truth, and that gave strength 

 and method to his mind. 



Finally his enthusiasm and the progress he made 

 was so great that he was permitted to give up medi- 

 cine and devote himself exclusively to mathematics. 

 He became acquainted with the Marquis Guido 

 Ubaldi, a cultivated geometrician, who employed him 



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