40 



tenuity of parts and difficulty of motion, are all that is requi- 

 site to the colligation of both. Since, however, each of the 

 elements is triple, the extremes require two media, and the 

 things themselves that are adjacent are bound together 

 through two powers. For solids, and these are things that 

 have triple contrary powers, are never co-adapted by one 

 medium." 



