428 Edward Livingston Youmans. 



are very unsafe hands at estimating evidence, where an appeal can- 

 not be made to actual eyesight. The intellectual part of our educa- 

 tion has nothing more important to do than to correct or mitigate 

 this almost universal infirmity this summary and substance of nearly 

 all purely intellectual weakness. To do this with effect needs all the 

 resources which the most perfect system of intellectual training can 

 command. Those resources, as every teacher knows, are but of 

 three kinds : first, models ; secondly, rules ; thirdly, appropriate 

 practice. The models of the art of estimating evidence are furnished 

 by science ; the rules are suggested by science ; and the study of sci- 

 ence is the most fundamental portion of the practice. . . . The 

 logical value of experimental science is comparatively a new subject, 

 yet there is no intellectual discipline more important than that which 

 the experimental sciences afford. Their whole occupation consists 

 in doing well, what all of us, during the whole of life, are engaged 

 in doing, for the most part badly. All men do not affect to be rea- 

 soners, but all profess, and really attempt, to draw inferences from 

 experience : yet hardly any one, who has not been a student of the 

 physical sciences, sets out with any just idea of what the process of 

 interpreting experience really is. If a fact has occurred once or 

 oftener, and another fact has followed it, people think they have got 

 an experiment, and are well on the road toward showing that the 

 one fact is the cause of the other. If they did but know the im- 

 mense amount of precaution necessary to a scientific experiment ; 

 with what sedulous care the accompanying circumstances are con- 

 trived and varied, so as to exclude every agency but that which is 

 the subject of the experiment or, when disturbing agencies cannot 

 be excluded, the minute accuracy with which their influence is calcu- 

 lated and allowed for, in order that the residue may contain nothing 

 but what is due to the one agency under examination ; if these things 

 were attended to people would be much less easily satisfied that 

 their opinions have the evidence of experience ; many popular 

 notions and generalizations which are in all mouths, would be 

 thought a great deal less certain than they are supposed to be ; but we 

 should begin to lay the foundation of really experimental knowledge, 

 on things which are now the subjects of mere vague discussion, 

 where one side finds as much to say and says it as confidently as an- 

 other, and each person's opinion is less determined by evidence than 

 by his accidental interest or prepossession. In politics, for instance, it 



