8 THE WORLD MACHINE 



investigator an implement of extraordinary utility. In a few 

 years the central force of the mechanism had been revealed by 

 Newton. An immense development in the domains of physics 

 and chemistry found a climax in the almost magical revelations 

 of the spectroscope, which filled as it were the last gap in the 

 circle of cosmic knowledge. So it was that in the brief space 

 of three or four centuries, and after an incalculable period of 

 blind groping, man was able at last to work out a rational theory 

 of the world, complete in all its essential details." 



It may well be, let it be said again, that our present ideas 

 of the cosmos, even in their larger outlines, are not yet final. 

 They may be infinitely expanded with the years and the know- 

 ledge to come. Yet in many considerable items of this know- 

 ledge we may be certain that finality and completeness have 

 been attained. Not so long as an intelligent race of beings 

 survives its precarious existence upon this globe shall we ever 

 cease to believe that the earth is a ball eight thousand miles 

 in diameter. We shall never cease to believe that it turns upon 

 its own axis, or that it booms through an orbit about the sun. 

 It is for ever inconceivable that we should ever change our 

 belief that the sun is a million times the bulk of the earth and 

 four hundred times further than the moon. It is inconceivable 

 that any subsequent knowledge will ever change our ideas of 

 the distance of the nearest visible stars. . 



This much we know. 



In a way this makes up, for us, three-quarters or four-fifths of 

 the cosmic landscape. It will abide. For when we speak of 

 this knowledge as being so very new, at the utmost three 

 hundred years old, in some sense we err. In some sense it is 

 as old as the race itself. Our ideas of the earth upon which 

 we dwell, of the orb of fire whose children, literally, we are 

 in a word, the whole world-picture, spacially at least, is the 

 result of geometrical methods of reasoning and measurement. 

 And geometry is old. It was old to the Greeks, who had it 

 from the Egyptians, and we gather that the Egyptians had 

 attained to a considerable stage of culture, intellectual and 

 otherwise, certainly seven thousand years ago. 



And again, what is all our geometry and mathematics, what 

 are all our inductions and deductions, our inferences and demon- 

 strations, but the codified experience, not merely of the human 



