744 THE PRINCIPLES OF SCIENCE. [CHAP. 



according to a wholly new law. After giving the natural 

 numbers for a finite time, it might suddenly begin to give 

 triangular, or square, or cube numbers, and these changes 

 might be conceived theoretically as occurring time after 

 time. Now if such occurrences can be designed and fore- 

 seen by a human artist, it is surely within the capacity of 

 the Divine Artist to provide for analogous changes of law 

 in the mechanism of the atom, or the construction of the 

 heavens. 



Physical science, so far as its highest speculations can 

 be trusted, gives some indication of a change of law in 

 the past history of the Universe. According to Sir W. 

 Thomson's deductions from Fourier's Tlieory of Heat, we 

 can trace down the dissipation of heat by conduction and 

 radiation to an infinitely distant time when all things will 

 be uniformly cold. But we cannot similarly trace the 

 heat-history of the Universe to an infinite distance in the 

 past. For a certain negative value of the time the formulae 

 give -impossible values, indicating that there was some 

 initial distribution of heat which could not have resulted, 

 according to known laws of nature, 1 from any previous 

 distribution. 2 There are other cases in which a considera- 

 tion of the dissipation of energy leads to the conception of 

 a limit to the antiquity of the present' order of things. 3 

 Human science, of course, is fallible, and some ovei sight 

 or erroneous simplification in these theoretical calculations 

 may afterwards be discovered ; but as the present state of 

 scientific knowledge is the only ground on which erroneous 

 inferences from the uniformity of nature and the supposed 

 reign of law are founded, I am right in appealing to the 

 present state of science in opposition to these inferences. 

 Now the theory of heat places us in the dilemma either of 



1 Professor Clifford, in his most interesting lecture on " The First 

 and Last Catastrophe" (Fortnightly Review, April 1875, p. 480, re- 

 print by the Sunday Lecture Society, p. 24), objects that I have 

 erroneously substituted " known laws of nature " for " known laws 

 of conduction of heat." I quite admit the error, without admitting 

 all the conclusions which Professor Clifford proceeds to draw ; but I 

 maintain the paragraph unchanged, in order that it may be discussed 

 in the Preface. 



2 Tait's Thermodynamics, p. 38. Cambridge Mathematical Journal, 

 vol. iii. p. 174. 



3 (Jlsrk Maxwell's Theory of Heat, p. 245. 



