i88 GREAT MEN OF SCIENCE 



work the whole material world, everything that we know to- 

 day concerning the phenomena of the heavens and of the 

 earth, from the nebulae to the geography of mosses on 

 granite rocks; and this is to be a work stimulating by the 

 liveliness of its language, and also entertaining. Every great 

 and important idea, which anywhere shines forth, must here 

 be given together with the relevant facts. It must represent 

 an epoch of the mental development of humanity as regards 

 its knowledge of nature.' This work, to the repeated re- 

 vision of which he devoted the greatest care, first began to 

 appear in 1845, ^"^ found a very large number of readers; it 

 occupied him until his death, at the great age of nearly ninety. 

 Humboldt was an investigating mind, though no single 

 great success stands to his credit as an investigator. In his 

 manysidedness he is similar to Leibniz, and also in the pecu- 

 liar nature of his personality, which enabled him to exert 

 great influence on his contemporaries, and also upon the 

 succeeding age. This gave him a high view of the calling of 

 a man of science, and also of the moral value of the results of 

 investigation; in this sense he also states, in his Kosmos, the 

 results of the investigation of nature as for friends of nature, 

 and not for exploiters. This power, rarely met with, of 

 emphasising the value of the achievement of past times, is 

 certainly of greater value than the production of a new dis- 

 covery, if the latter does not meet with people who are edu- 

 cated to a proper understanding of it. 



HUMPHREY DAVY {1778-1820) 

 JACOB BERZELIUS {1779-1848) 



These are the two great men of science who were the first 

 to use the electric current, so freely produced by Volta's 

 pile, for thorough and fundamental chemical investigation; 



