326 Agricultural Chemistry. 



We must never forget that any cliange in our methods or in 

 the direction of men's thoughts, whether in science or in arts or 

 professions, can only be very gradually effected, and that the 

 refutation of errors which are held as truths is infinitely difficult, 

 because truth itself appears to be error. In all ages and on 

 every such occasion the old falsehood has stood at the door 

 when a nev/ truth desired admission. The true doctrine is to be 

 recognised by this, that it has roots and that it grows. 



To myself, in regard to the chemical theory of agriculture, I 

 believe I may apply, without presumption, what Macaulay says 

 of Bacon : — 



" He was not the maker of that road ; lie was not the discoverer of that 

 road ; he was not the x^evson who first snrvej'ed and mapped that road. But 

 he was the person who first called the public attention to an inexhaustible 

 mine of wealth, which had been utterly neglected, and which was accessible 

 by that road alone. By doing so he caused that road, Avhich had previously 

 been trodden only by peasants and higglers, to be frequented by a higher order 

 of travellers." 



Munich, April, 1856. 



