I PROLOGUE 3 



honourable adversaries that any heat of which 

 signs may remain was generated, in accordance 

 with the law of the conservation of energy, by the 

 force of their own blows, and has long since been 

 dissipated into space. 



But, however the polemical concomitants of 

 these discussions may be regarded or better, dis- 

 regarded there is no doubt either about the im- 

 portance of the topics of which they treat, or 

 as to the public interest in the " Controverted 

 Questions " with which they deal. Or rather, 

 the Controverted Question ; for disconnected as 

 these pieces may, perhaps, appear to be, they are, 

 in fact, concerned only with different aspects of a 

 single problem, with which thinking men have 

 been occupied, ever since they began seriously to 

 consider the wonderful frame of things in which 

 their lives are set, and to seek for trustworthy 

 guidance among its intricacies. 



Experience speedily taught them that the 

 shifting scenes of the world's stage have a perma- 

 nent background ; that there is order amidst the 

 seeming confusion, and that many events take 

 place according to unchanging rules. To this 

 region of familiar steadiness and customary regu- 

 larity they gave the name of Nature. But, at the 

 same time, their infantile and untutored reason, 

 little more, as yet, than the playfellow of the 

 imagination, led them to believe that this tangible, 

 commonplace, orderly world of Nature was sur- 



