ARGUMENT CONTINUED. 35 



he taken in conjunction (the attention is not to rest upon 

 them, but they are to be taken in conjunction) with the 

 unexceptionable evidences which we possess, of skill, 

 power, and benevolence, displayed in other instances ; 

 which evidences may, in strengtn, number, and variety, be 

 such ; and may so overpower apparent blemishes, as to in- 

 duce us, upon the most reasonaule ground, to believe, that 

 these last ought to be referred to some cause, though we 

 be ignorant of it, other than defect of knowledge or of be- 

 nevolence in the author. 



11. There may be also parts of plants and animals, as 

 there were supposed to be of the watch of which, in some 

 instances, the operation, in others, the use is unknown, 

 These form different cases ; for the operation may be un- 

 known, yet the use be certain. Thus it is with the lungs of 

 animals It does not, I think, appear, that we are acquainted 

 with the action of the air upon the blood, or in what man* 

 ner that action is comiiiunicated by the lungs ; yet we tind 

 that a very short suspension of their office destroys the 

 life of the anirnal. In this case, therefore, we may be said 

 to know the use, nay, we experience the necessity of the 

 organ, though we be ignorant of its operation. Nearly the 

 same thing may be observed of what is called the lympha- 

 tic system. We suffer grievous inconveniences from its dis- 

 order, without being informed of the office which it sus- 

 tains in the economy of our bodies. There may possibly 

 also be some few examples of the second class, in which, 

 not only tiie operation is unknown, but in Vv'hich experi- 

 ments may seem to prove that the part is not necessary ; 

 or may leave a doubt, how far it is even useful to the plant 

 or animal m which it is found. This is said to be the case 

 with the spleen ; which has been extracted from dogs, with- 

 out any sensible injury to their vital functions. Instances 

 of the former kind, namely, in which we cannot explain 

 the operation, may be numerous ; for they v.ili be so in 

 proportion to our ignorance. They will be more or fewer 

 to different persons, and in different stages of science. Every 

 improvement of knowledge diminishes their number. 

 There is hardly, peihaps, a year passes, that does not, in 

 the works of nature, bring some operation, or some mode 

 of operation, to light, which was before undiscovered, pro- 

 bably unsuspected instances of the second kind, namely, 

 where tne part appears to be totally useless, I believe to be 

 extremely rare ; compared with the number of those, of 

 which the use is evident, they are beneath any assignable 



