Mental Discipline in I Education. 427 



lifr it is our most pressing interest to find out the truth about all the 

 matters we are concerned with. If we are farmers we want to find 

 what will truly improve our soil ; if merchants, what will truly in- 

 fluence the markets of our commodities; if judges, or jurymen, or 

 advocates, who it was that truly did an unlawful act, or to whom a 

 disputed right truly belongs. Every time we have to make a new 

 resolution or alter an old one, in any situation in life, we shall go 

 wrong unless we know the truth about the facts on which our resolu- 

 tion depends. Now, however different these searches for truth may 

 look, and however unlike they really are in their subject-matter, the 

 methods of getting at truth, and the tests of truth, are in all cases 

 much the same. There are but two roads by which truth can be 

 discovered : observation and reasoning ; observation, of course, in- 

 cluding experiment. We all observe, and we all reason, and there- 

 fore, more or less successfully, we all ascertain truths : but most of 

 us do it very ill, and could not get on at all were we not able to fall 

 back on others who do it better. If we could not do it in any degree, 

 we should be mere instruments in the hands of those who could : 

 they would be able to reduce us to slavery. Then how shall we best 

 learn to do this ? By being shown the way in which it has already 

 been successfully done. The processes by which truth is attained, 

 reasoning and observation, have been carried to their greatest known 

 perfection in the physical sciences. As classical literature furnishes 

 the most perfect types of the art of expression, so do the physical 

 sciences those of the art of thinking. Mathematics, and its applica- 

 tion to astronomy and natural philosophy, are the most complete ex- 

 ample of the discovery of truths by reasoning ; experimental science, 

 of their discovery by direct observation. In all these cases we know 

 that we can trust the operation, because the conclusions to which it 

 has led have been found true by subsequent trial. It is by the study 

 of these, then, that we may hope to qualify ourselves for distinguish- 

 ing truth, in cases where there do not exist the same ready means of 

 verification. 



In what consists the principal and most characteristic difference 

 between one human intellect and another ? In their ability to judge 

 correctly of evidence. Our direct perceptions of truth are so limited ; 

 we know so few things by immediate intuition, or, as it used to be 

 called, by simple apprehension that we depend for almost all our 

 valuable knowledge on evidence external to itself; and most of us 



