108 JAMES CLERK MAXWELL. [CHAP. V. 



Hamilton especially he received an impulse which 

 never lost its effect. Though only sixteen when he 

 entered the Logic Class, he worked hard for it, as his 

 letters show; and from the Class of Metaphysics, 

 which he attended in the following year, his mind 

 gained many lasting impressions. 1 ; His boundless 

 curiosity was fed by the Professor's inexhaustible 

 learning ; his geometrical imagination predisposed him 

 to accept the doctrine of " natural realism ;" while his 

 mystical tendency was soothed by the distinction 

 between Knowledge and Belief. The doctrine of a 

 muscular sense gave promise of a rational analysis of 

 the active powers. However strange it may appear 

 that a born mathematician should have been thus 

 influenced by the enemy of mathematics, the fact is 

 indisputable that in his frequent excursions into the 

 region of speculative thought, the ideas received from 

 Sir William Hamilton were his habitual vantage- 

 ground ; the great difference being, that while Sir 

 William remained for the most part within the sphere 

 of Abstract Logic, Maxwell ever sought to bring each 

 " concept" to the test of fact. Sir William in turn 

 took a genial interest in his pupil, who was indeed the 

 nephew of an old friend Sheriff Cay having at one 

 time been a constant companion and firm ally of Sir 

 William's. 2 This is perhaps the most striking example 



1 A slight illustration of his devotion to Sir William's teaching, 

 and also of his powers of endurance, is afforded by the following 

 incident : One day he sprained his ankle badly on the College stair- 

 case ; but, instead of going home, he attended Sir William Hamilton's 

 class as usual, and sat through the hour as if nothing had happened. 



2 John Lockhart had made a third as the comrade of both. 



