194 LETTER-FILES OF S. W. JOHNSON 



written in books and may live in history, but what is done 

 in agriculture must live in the life of the people. 



The next day Professor Johnson delivered, before 

 the Board, a lecture on "Guiding Ideas in the Use of 

 Fertilizers," in which he clearly defined some of the 

 problems confronting the agriculturist, and made an 

 earnest appeal for the application of scientific prin- 

 ciples to everyday problems : 



The best method of attaining truth is to endeavor earnestly 

 but honestly to disprove what appears to be true. If you set 

 out with the idea that you know a thing, you can very easily 

 convince yourself that you do, particularly if you have 

 admiring friends who know nothing about the subject. That 

 lies in human weakness. The only way to be certain you have 

 got at the truth is to go counter to the current of self- 

 complacency. If you can sit down deliberately with your 

 supposed facts, and with your theories, and try by every 

 imaginable test to find where they do not harmonize, or where 

 they do not satisfy strict logic, then and not until then can 

 you be pretty certain that you stand fair and square on that 

 subject. That is the temper of those who are educated in 

 what we call the scientific methods of investigation, especially 

 as taught in the German schools. It was in that spirit that 

 Baron Liebig instructed the students who gathered in his 

 laboratory from all quarters of the globe to learn the art of 

 making discoveries in science. They were set to testing the 

 truth of some idea, or the correctness of some fact, or else to 

 make new observations and discover new facts to lead to new 

 ideas. It was not the novelty or the glory of discovery, but 

 the genuineness of discovery that was regarded as of first 

 importance. He listened patiently to their accounts of each 

 day 's progress, considered their plan of investigation, saw the 

 apparatus or arrangements they devised, witnessed the obser- 

 vations they were led to, and heard the theories they imagined. 



