Xll PREFACE TO THE SECOND AND THIRD EDITIONS. 



advantages, the public have long regarded my imperfectly 

 executed undertaking with friendly partiality. 



The second edition of the " Ansichten der Natur" was 

 prepared by me in Paris in 1826 ; and at the same time two 

 fresh treatises were added, one an Essay on the Structure 

 and mode of Action of Yolcanoes in different regions of the 

 earth ; and the other on the " Vital Power," bearing the 

 title " Lebenskraft, oder der rhodische Genius." During 

 my long stay at Jena, Schiller, in the recollection of his 

 youthful medical studies, loved to converse with me on 

 physiological subjects ^ and the considerations in which I 

 was then engaged on the muscular and nervous fibres when 

 excited by contact with chemically different substances, often 

 gave a more specific and graver turn to our discourse. The 

 " Ehodian Genius" was written at this time : it appeared 

 first in Schiller's ' ' Horen," a periodical journal ; and it was 

 his partiality for this little work which encouraged me to 

 allow it to be reprinted. My brother, in a letter forming 

 part of a collection which has recently been given to the 

 public (Wilhelm von Humboldt's Briefe an eine Preundin, 

 Th. ii. S. 39), touches tenderly on the subject of the memoir 

 in question, but adds at the same time a very just remark : 



