NATURAL THEOLOGY. 71 



causes.'^ Instead of the parts of a plant or animal, 

 or the particular structure of the parts, having been 

 intended for the action or the use to which we 

 see them applied ; according to this theory, they 

 have themselves grown out of that action, sprung 

 from that use. The theory therefore dispenses 

 with that which we insist upon, the necessity, in 

 each particular case, of an intelligent, designing 

 mind, for the contriving and determining of the 

 forms which organized bodies bear. Give our 

 philosopher these appetencies ; give him a portion 

 of living irritable matter (a nerve, or the clipping 

 of a nerve,) to work upon : give also to his incipi- 

 ent or progressive forms the power, in every stage, 

 of their alteration, of propagating their like ; and, 

 if he is to be believed, he could replenish the 

 world with all the vegetable and animal produc- 

 tions w^hich we at present see in it. 



The scheme under consideration is open to the 

 same objection with other conjectures of a similar 

 tendency, viz. a total defect of evidence. No 

 changes, like those which the theory requires, have 

 ever been observed. All the changes in Ovid's 



^^ In on J sense this doctrine (if it deserves the namej of appe- 

 tencies ca.n hardly be said to supersede final catises. For sup- 

 pose the conatus or appetency to have formed an eye, such as we 

 now have it, and constructed as we know it to be, all its uses 

 continue; it is calculated to perform the office required, — to sup- 

 ply that, the desire of supplying which is supposed so have produ- 

 ced it. Stating that desire caused the production appears only to 

 be a covert and somewhat absurd mode of stating the doctrine of 

 final ca'ises. 



