56 LETTER IV. 



and disinterested pleasure in his speculations which 

 ought to exempt them from such questioning ; com- 

 municating as they do, to his own mind the purest 

 happiness (after the exercise of the benevolent and 

 moral feelings), of which nature is susceptible, and 

 tending to the injury of no one ; he might surely 

 allege this as a sufficient and direct reply to those 

 who, having themselves little capacity, and less re- 

 lish for intellectual pursuits, are constantly repeating 

 upon him this inquiry. But if he can bring himself 

 to descend from this high but fair ground, and justify 

 himself, his pursuits, and his pleasures in the eyes of 

 those around him, he has only to point to the history 

 of all science, where speculations, apparently the 

 most unprofitable, have almost invariably been those 

 from which the greatest practical applications have 

 emanated. What, for instance, could be apparently 

 more unprofitable than the dry speculations of the 

 ancient geometers on the properties of the conic 

 sections, or than the dreams of Kepler (as they would 

 naturally appear to his contemporaries) about the 

 numerical harmonies of the universe. Yet these are 

 the steps by which we have risen to a knowledge of 

 the elliptic motions of the planets, and the law of 

 gravitation, with all its splendid theoretical conse- 

 quences, and its inestimable practical results. The 

 ridicule attached to ' Swing-swangs' in Hooke's time 

 did not prevent him from reviving the proposal of the 

 pendulum as a standard of measure, since so ad- 

 mirably wrought into practice by the genius and per- 

 severance of Captain Kater ;— nor did that which 



