300 THE COMING OF MAN 



The moon, too, was always changing its position, 

 sometimes travehng low, sometimes high. They 

 noticed that it changed its shape from day to day, 

 from a thin crescent into a round, full moon, then 

 changing back, until in twenty-eight days it would 

 begin again as a narrow silver crescent in the w^est. 

 You see it change in this way yourselves. 



All those things they pondered over, until some 

 whose eyes were keen to notice the things in the 

 world as well as those in the sky, and whose minds 

 were keen to think about what they saw, concluded 

 that the world must be round like a ball. But they 

 still thought of it as fixed in space, with the sun, 

 moon and stars revolving about it. They believed 

 that the world was the center of all things; and when 

 they noticed that the stars did not seem to change 

 their positions in regard to each other, they thought 

 that those twinkling stars must be fastened to the 

 dome of the heavens, which itself revolved around 

 the earth, carrying the stars with it. 



Men thought this for hundreds of years. If you 

 had Uved then, you would have been taught just 

 what the rest believed. But you might have been 

 one of those who saw more clearly than the others, 

 and could not believe in a fixed earth with a revolving 

 dome above it. You might have wondered about it, 

 and tried to understand it better. 



That is just what Copernicus did. He was a 

 searcher for truth who was born in Poland. He 

 watched the movements of the sun, the moon and 

 the stars, and after thinking about them for a long 

 time he announced to the world that the sun was the 



