352 Dr. Percival on the Pur/uits 



parts, and fertile imagination, generally engages 

 in philofophical refearches, with too much impe- 

 tuofityi and it' he be fortunate in the attainment 

 of a few leading facts, he fupplies all remaining 

 deficiencies by conjefture and hypothefis. But 

 fhould his career be obftruded by contradidory 

 phaenomena, he quits the iludy of nature with 

 difguftj and concludes that all is uncertainty, 

 becaufe he has had the mortification to find him- 

 felf miftaken. A fcepticifm like this, founded 

 in pride and indolence, is equally fubverfive 

 both of fpeculation and of acftion. We can apply 

 to no branch of human learning, which is fecurc 

 from illufion, or exempt from controverfyj nor 

 engage in any plan of life with undeviating judg- 

 ment, and uninterrupted fuccefs. So true is the 

 fentiment of the Roman poet. 



Nunquam quifquam ita bene fubdufta ratione ad vitam fuit, 

 Quin res, aetas, ufus, femper aliquid apportet novi ; 

 Aliquid admoneat : ut ilia, qua te fcire credas, nefcias, 

 Et qu£ tibi putaris prima in experiundo repudies. 



Terent. 



But as difappointments in life often furnilh 

 the bed leflbns of vvifdom, fo thofe in philofophy 

 may, frequently, be applied to the promotion of 

 fcience. In experimental purfuits, which are 

 not undertaken at random, but with confident 

 and rational views, we neceflarily form a pre- 

 conception of the induftion to be eftablifhed. 

 If the trials fucceed, in which we are engaged, 



our 



