XLiv.] EEMAEKS ON THE HISTORY OF SCIENCE. 223 



laws of force were applied by deductive reasoning to 

 explain the laws of heat. 



It is, however, roughly and approximately true, that the 

 order in which the sciences have been historically evolved 

 corresponds to the logical order of their arrangement, be- 

 ginning with simple and general laws and going on to 

 more complex and special ones. But, in addition to what 

 has been said in the last paragraph, this must be under- 

 stood with two other important qualifications. 



In the first place, though each science is logically based The logical 



, 1 , • 1 1 1 ■ 1-1 relations of 



on that more simple and general science which comes g^ science 

 before it in the series, yet this is not always, nor generally, are not 

 apparent at the time when the study of the science is first obvious 

 begun. Most sciences have been begun independently, ^^ ^'■^*- 

 and without any reference in the minds of their founders 

 to any other science. In most cases each science has 

 been commenced, and has made considerable progress, 

 before its students became aware of its relation with 

 that science w^hich comes next before it in the series, 

 and on which it is logically based. This is not the 

 case with dynamics : dynamics is unable to take a single 

 step without the aid of mathematics. But it is true 

 of the sciences of observation and experiment. Thus, 

 chemistry is based on the dynamical group of sciences, 

 especially on those of electricity and heat : but this 

 did not prevent chemistry from making a beginning, A science 

 and being in a tolerably forward state, before electro- "^.^uate 

 chemistry and thermo-chemistry were thought of. In indepen- 

 the same way, biology is based on chemistry ; for such 

 physiological laws as those of nutrition and of respiration 

 involve chemical laws, and cannot be stated without pre- 

 supposing them : and yet biology had made considerable 

 progress before this relation was perceived. "Were it not 

 possible for a science to be thus begun independently, the 

 progress of science would have been much slower than it 

 actually has been. The fact is, however, that most sciences and 

 have been begun independently; and the perception of^^g^^j^^^g 

 the true relation of each science to the rest, and of the so. 

 right place of each in the scientific scale, has been, not an 



