268 HEAT ONLY A SENSATION. 



forming a part of, or otherwise affecting the quan- 

 tity of matter in bodies ; and, therefore, all such 

 speculations as, " whether the quantity of matter 

 in the sun be diminished in consequence of the 

 light which the sun gives out, in the same man- 

 ner that the oil in a lamp is consumed by the 

 burning of the lamp," are absurd. The light of 

 the lamp does not consume the oil, and as little 

 does the light of a fire consume the fuel. The 

 light is, in these cases, only one of the appear- 

 ances attendant upon the decomposition of mat- 

 ter, and if it measure any thing it measures only 

 the rapidity with which the decomposition takes 

 place. Farther, as light is reflected from sur- 

 faces, and reflected from them though it be invi- 

 sible previous to the reflection, the light of the 

 sun may be a reflection from the sun, or the sun's 

 atmosphere, which comes invisibly to that lumi- 

 nary from some far distant source. The colours 

 which we observe directly in nature, are not 

 visible, and, therefore, do not exist at any point 

 between the coloured object and the eye ; and re- 

 flected colours, such as those of the face in a 

 mirror, exist nowhere between the face which 

 is reflected, and the eye that sees the reflection. 



So also, in the case of heat, we can never ob- 

 serve it as any thing else than an accompaniment 

 of some action, and intense in proportion to the 

 intensity of that action. From what we can ob- 

 serve and judge of the other appearances, by 

 which cold and heat, even heat up to the most 

 intense combustion, all that we can say is, that 

 absolute cold appears to be but another name for 

 absolute rest ; and absolute heat, absolute motion 

 and conflict. 



