14 Systems of Equality. Bk. iii. 



that a carnation long before it reached the size of 

 a cabbage would not be supported by its stalk. ; 

 but I only know this from my experience of the 

 weakness and want of tenacity in the materials 

 of a carnation-stalk. There might be substances 

 of the same size that would support as large a 

 head as a cabbage. 



The reasons of the mortality of plants are at 

 present perfectly unknown to us. No man can 

 say why such a plant is annual, another biennial, 

 and another endures for ages. The whole affair 

 in all these cases, in plants, animals, and in the 

 human race, is an affair of experience ; and I 

 only conclude, that man is mortal, because the 

 invariable experience of all ages has proved the 

 mortality of that organized substance, of which 

 his visible body is made. 



" What can we reason but from what we know ?" 



Sound philosophy will not authorize me to alter 

 this opinion of the mortality of man on earth, 

 till it can be clearly proved that the human race 

 has made, and is making, a decided progress to- 

 wards an illimitable extent of life. And the chief 

 reason why I adduce the two particular instances 

 from animals and plants was to expose and illus- 

 trate, if I could, the fallacy of that argument, 

 which infers an unlimited progress merely because 

 some partial improvement has taken place, and 

 that the limit of this improvement cannot be pre- 

 cisely ascertained. 



The capacity of improvement in plants and 



