JUSTUS VON LIEBIG. 661 



a man can only make valuable that whicli he learns ■without 

 trouble, or acquires readily, for which, as we say, he has a natural 

 gift, if he learns many other things in addition, which perhaps 

 cost him more trouble to acquire than other people. 



Lessing says that talent really is will and icork, and I am very 

 much inclined to agree with him. 



The lectures of Gay-Lussac, Thenard, Dulong, etc., in the Sor- 

 bonne, had for me an indescribable charm ; the introduction 

 of astronomical or mathematical method into chemistry, which 

 changes every problem when possible into an equation, and as- 

 sumes in every uniform sequence of two phenomena a quite cer- 

 tain connection of cause and effect, which, after it has been 

 searched for and discovered, is called " explanation " or " theory," 

 had led the French chemists and physicists to their great discov- 

 eries. This kind of " theory " or " explanation " was as good as 

 unknown in Germany, for by these expressions was understood 

 not something " experienced," but always something which man 

 must add on and which he fabricates. 



French exposition has, through the genius of the language, a 

 logical clearness in the treatment of scientific subjects very diffi- 

 cult of attainment in other languages, whereby Thenard and Gay- 

 Lussac acquired a mastery in experimental demonstration. The 

 lecture consisted of a judiciously arranged succession of phe- 

 nomena — that is to say, of experiments whose connection was com- 

 pleted by oral explanations. The experiments were a real delight 

 to me, for they spoke to me in a language I understood, and they 

 united with the lecture in giving definite connection to the mass 

 of shapeless facts which lay mixed up in my head without order 

 or arrangement. The antiphlogistic or French chemistry had, it 

 is true, brought the history of chemistry before Lavoisier to the 

 guillotine ; but one observed that the knife only fell on the shad- 

 ow, and I was much more familiar with the phlogistic writings 

 of Cavendish, Watt, Priestley, Kirwan, Black, Scheele, and Berg- 

 mann, than with the antiphlogistic ; and what was represented in 

 the Paris lectures as new and original facts appeared to me to be 

 in the closest relation to previous facts, so much so, indeed, that 

 when the latter were imagined away the others could not be. 



I recognized, or more correctly perhaps the consciousness 

 dawned upon me, that a connection in accordance with fixed 

 laws exists not only between two or three, but between all chemi- 

 cal phenomena in the mineral, vegetable, and animal kingdoms ; 

 that no one stands alone, but each being always linked with an- 

 other, and this again with another, and so on, all are connected 

 with each other, and that the genesis and disappearance of things 

 is an undulatory motion in an orbit. 



What impressed me most in the French lectures was their 



