GUSTAV MAGNUS. 15 



of activity of the human mind, and where, therefore, 

 a construction a priori from the psychological laws 

 seems much more possible than in nature, it has come 

 to be understood that we must first know the facts, be- 

 fore we can establish their laws. 



Gustav Magnus's development happened during the 

 period of this struggle ; it lay in the whole tendency 

 of his mind, that he whose gentle spirit usually en- 

 deavoured to reconcile antagonisms, took a decided part 

 in favour of pure experience as against speculation. 

 If he forbore to wound people, it must be confessed 

 that he did not relax one iota of the principle which, 

 with sure instinct, he had recognised as the true one ; 

 and in the most influential quarters he fought in a 

 twofold sense ; on the one hand, because in physics it 

 was a question as to the foundations of the whole of 

 natural sciences ; and on the other hand, because the 

 University of Berlin, with its numerous students, had 

 long been the stronghold of speculation. He con- 

 tinually preached to his pupils that no reasoning, 

 however plausible it might seem, avails against actual 

 fact, and that observation and experiment must de- 

 cide ; and he was always anxious that every practicable 

 experiment should be made which could give practical 

 confirmation or refutation of an assumed law. He did 

 not limit in any way the applicability of scientific 

 methods in the investigation of inanimate nature, but 



