28 OF REPRODUCTION 



chain of fucceflive effed;s, provided we have a 

 clear conception of thi dependence of thefe ef- 

 fedis upon each other, and of their mutual rela- 

 tions. 



But, when a particular effed appears not to 

 have any dependence upon more general efFeds, 

 or h s no analogy to thofe already known, we are 

 then totally unable to give any explication of fuch 

 efFed ; becaufe we have no fnnilar object with 

 which it can be compared. We cannot explain 

 a general caufe, becaufe it equally exifts in every 

 object; and, on the coutraiy, we can give no 

 account of a fiagle or ifolated eftet^ ; becaufe 

 the fame quality exifts not in any other fubjedl. 

 To explain a general caufe, we muft difcover one 

 flill more general ; bic a fmgle and detached 

 effed; may be iliuitnited by the difcovery of an 

 analogous efFed, which experience or accident 

 may exhibit. 



There is Hill another kind of queftion, which 

 may be called a queftion of fad. For example, 

 why do trees, dogs, &c. exift ? All queftions of 

 this kind are perfedly infolvable; for thofe who 

 folve them by final caufes confider not that they 

 miftake the effed for the caufe : The relation of 

 particular objeds to ourfelves has no connedion 

 with their origin. Moral affinity or fitnefs can 

 never become a phyfical reafon. 



Queftions in which we employ the word Whj, 

 ought to be carefully diftinguifhed from thofe 



in 



