94 THE ANATOMY OF SCIENCE 



ciple of the inclined plane. Yes, but how would 

 we know that there is any connection between 

 the pull exerted by a body on an inclined plane 

 and the idea of perpetual motion, were it not 

 for the work of men like Stevinus? Such deduc- 

 tions of the unknown from the apparently ir- 

 relevant kno\M:i seem to be the very gist of the 

 scientific method. The motto which he places 

 above his diagram, "A wonder, and yet no won- 

 der," is an epigrammatic statement of this same 

 thought. 



It was not long after the appearance of 

 the work that I have just mentioned that the 

 greater science of dynamics was born in the 

 mind of Galileo. We who step daily upon the 

 accelerator, and note by our speedometers 

 the immediate change in our velocity, find it 

 hard to realize that this notion was so new in 

 the time of Galileo that he found it necessary 

 to coin the word "acceleration." His discovery 

 that, except for the resistance of the air, a body 

 falls with a constantly increasing velocity, or, 

 in other words, with a constant acceleration, 

 and that any two bodies, regardless of differ- 

 ence in weight or in other properties, when 

 started together always keep together in fall- 

 ing, marked the beginning of the new science. 



