326 APPENDIX. 



that it may be created and annihilated. Now, we 

 have no idea of matter being created and anni 

 hilated by any natural cause, (for under all its 

 variety of forms, matter is matter still) ; then what 

 kind of a substance must Heat be, to be produced 

 and destroyed by so many causes ? Why, truly, 

 nobody can tell : for it must have a property which 

 matter has not. Heat is, then, probably a quality: 

 for qualities we know can easily be created and 

 annihilated. And, if Heat be a quality, it must 

 have matter to exist in ; so that, if we apply any 

 of the causes producing Heat, no Heat is produced 

 unless there be some matter to receive it. This, 

 therefore, is the result of our inquiries into the 

 -nature of Heat. 



We have also seen, that Light may be produced 

 by particular means, the solar rays for instance : it 

 may likewise be destroyed, as has been previously 

 shewn. The method of reasoning just applied to 

 Heat, may with equal propriety be used here : and 

 this will induce us to conclude that Light, instead 

 of being a fluid per sr, as has been sometimes 

 conjectured, is a quality, and can no more exist 

 independently of matter than Heat can. 



Whether these conclusions may be safely relied 

 on, is not for us to determine : the great myste- 

 rious BEING who made and governs the universe, 

 has set a part only of the chain of causes in our 

 view ; and we find that as HK himself is too high 

 for our comprehension, so His more immediate 

 instruments are also involved in an obscurity that 

 ur feeble endeavours are not able to dissipate. 



However, 



