286 MASSACHUSETTS AGRICULTURE. 



of his art in the world. The best practice may be empyrical, 

 biit experiment is worthless if it be not philosophical. It is the 

 want of this logical faculty that leads so many persons to 

 believe they have discovered the cause of a thing, when they 

 have only discovered one of its accompaniments. 



The difficulties which most men encounter when they are 

 experimenting on any subject, are what Lord Bacon terms 

 " the idols of the mind." An individual discovers a peculiar 

 symptom, for example, upon the vine or the tuber of the potato 

 plant, while it is effected with disease ; and this gives rise to a 

 conjecture, and upon this conjecture he builds a theory. He 

 then commences a sort of special pleading for his own hypothesis, 

 and ends in convincing himself that he has made a great 

 discovery. His error proceeds from using his conjectures for 

 his premi c es, and building his system upon them before he has 

 established his facts. It is in this way that men are constantly 

 deceiving themselves and the public. 



This is not the way to investigate truth : it is the way which 

 has always been used to establish error. It leads one to set 

 aside all evidence unfavorable to his assumption, as a corrupt 

 judge rules out of court the evidence of those witnesses who 

 are opposed to his own designs. Many very erroneous theories 

 have been built up by this method of establishing a position. 

 Their advocates, however, often perform an important service 

 to science, by stimulating others to examine the opposite side ; 

 and by their coinpetitory reasoning and experiment, a great 

 deal of useful information is brought to light. 



The legislative committee have pursued their investigations 

 in a true philosophical spirit, and with a full comprehension of 

 all the difficulties of the subject. But this investigation cannot 

 be successfully pursued by the most capable persons, unless they 

 can be furnished with a motive to devote a great part of their 

 time and attention to it. The best course would be to author- 

 ize the committee to select some competent individual, and offer 

 him a pecuniary inducement to attend to a series of experi- 

 ments in relation to the subject, during a certain number of 

 years, making it his duty to superintend all the operations, note 

 the symptoms, the beginning and the progress of the disease, 

 and all the circumstances attending it, and make semi-annual 

 reports. 



