152 CORRELATION OF PHYSICAL FORCES. 



are mere results of collected and collated observations, and 

 all our generalising philosophy is based on an unconscious 

 belief in continuity. In such cases, though the word ' law ' is 

 used, all that can be predicated is that, as far as experience 

 goes, certain results follow certain arrangements of matter. 

 Many of these supposed laws have been found to be erroneous 

 or to be no laws at all, e.g. Marriotte's law as to the 

 expansion of gases, Gay-Lussac's as to the chemical relations 

 of the volumes of gases, &c. ; the word * law/ therefore, except- 

 ing the term be applied to mathematical truths, is merely a 

 generalised expression of certain observed results which as far 

 as our experience goes are invariable ; and when we personify 

 the term ' law/ as by talking of effects taking place in obedience 

 to a law, we use an inaccurate expression, only justifiable as 

 metaphor ; but this use of the term has so warped men's minds 

 that the mass of even educated people believe in law as some- 

 thing separate from and governing the phenomena, the latter 

 being supposed to be subject to the law, whereas this is only 

 an abstract definition of relations derived from the observa- 

 tion of the phenomena themselves. The word ' nature ' is 

 still more personified ; instead of being used to denote, what 

 alone it can denote- namely, things as we see, hear or feel, 

 them, and their relations ascertained by comparison and 

 abstraction nature is treated as a sort of superintending 

 angel who enjoins this, permits that, and forbids the other. 



It may be that natural phenomena, as we come to know 

 them more thoroughly, may resolve themselves into forms 

 which may be mathematically expressed, and which may have 

 the certainty of mathematical truths, as the laws of Kepler and 

 Newton's law of gravitation now appear to have; but we are far 

 from that at present so far as regards the greater number of 

 phenomena, particularly those exhibited by molecular and 

 physiological effects. To bring all within the domain of what 

 are termed necessary truths would require omniscience. 



