RESULTS AND LIMITS OF SCIENTIFIC METHOD. 439 



some oversight or erroneous simplification in these theo- 

 retical calculations may afterwards be discovered ; but as 

 the present state of scientific knowledge is the only ground 

 on which erroneous interpretations of the uniformity of 

 nature and the reign of law are founded, I am right in 

 appealing to the present state of science in opposition to 

 these interpretations. Now the theory of heat places us 

 in the dilemma either of believing in Creation at an assign- 

 able date in the past, or else of supposing that some 

 inexplicable change in the working of natural laws then 

 took place. Physical science gives no countenance to the 

 notion of infinite duration of matter in one continuous 

 course of existence. And if in time past there has been 

 a discontinuity of law, why may there not be a similar 

 event awaiting the world in the future. Infinite ingenuity 

 could have implanted some agency in matter so that it 

 might never yet have made its tremendous powers mani- 

 fest. We have a very good theory of the conservation of 

 energy, but the foremost physicists do not deny that there 

 may possibly be forms of energy, neither kinetic nor poten- 

 tial, and therefore of unknown nature 1 . 



We can imagine reasoning creatures dwelling in a world 

 where the atmosphere was a mixture of oxygen and in- 

 flammable gas like the fire-damp of coal mines. If devoid 

 of fire, they might have lived on through long ages in 

 complete unconsciousness of the tremendous forces which a 

 single spark could call into play. In the twinkling of an 

 eye new laws might have come into action, and the poor 

 reasoning creatures who were so confident in their know- 

 ledge of the uniform conditions of their world, might have 

 had no time even to speculate upon the overthrow of all 

 their theories. Can we with our finite knowledge be 

 sure that such an overthrow of our theories is impossible 1 



i Maxwell's 'Theory of Heat/ p. 92. 



