CAUSE OF ITS FAILURE. 85 



any point, comes to the same point again, so that 

 by a continuous progression, the last point becomes 

 the first. So that, as was before stated, it is not 

 surprising that the circle should be the principle of 

 all wonderful properties." 



Aristotle afterwards proceeds to explain more 

 specially how he applies the properties of the circle 

 in this case. " The reason," he says, in his fourth 

 Problem, " why a force, acting at a greater distance 

 from the fulcrum, moves a weight more easily, is, 

 that it describes a greater circle." He had already 

 asserted that when a body at the end of a lever is 

 put in motion, it may be considered as having two 

 motions ; one in the direction of the tangent, and 

 one in the direction of the radius; the former motion 

 is, he says, according to nature, the latter, contrary 

 to nature. Now in the smaller circle, the motion, 

 contrary to nature, is more considerable than it is 

 in the larger circle. "Therefore," he adds, "the 

 mover or weight at the larger arm will be trans- 

 ferred further by the same force than the weight 

 moved, which is at the extremity of the shorter arm." 



These loose and inappropriate notions of " na- 

 tural" and " unnatural" motions, were unfit to lead 

 to any scientific truths ; and, with the habits of 

 thought which dictated these speculations, a per- 

 ception of the true grounds of mechanical proper- 

 ties was impossible. 



Thus, in this instance, the error of Aristotle was 

 the neglect of the Idea appropriate to the facts, 



