358 ALEXANDER VON HUMBOLDT. 



Bockh, on May 12, 1858, the manuscript of the shorter intro- 

 duction to the fifth volume, in which he ' dilates for the last, 

 time on natural philosophy.' An outline of the history of 

 natural philosophy, forming the subject of the introduction to 

 the third volume, had been treated of in the lectures upon 

 physical geography, and it is possible that in the same way as he 

 touched upon philosophy in the ' History of the Eise and Pro- 

 gress of Science,' in the second volume, so now this was written 

 to form an introduction to the mass of collected facts. But 

 it served also another purpose ; it was an attempt on the 

 part of the author to bring himself into accord with the spirit 

 of the age, towards which he could no longer conceal from 

 himself that he stood at some variance. If, as we have seen, 

 6 Cosmos,' in its scientific aspect, breathes the spirit of an 

 empiric age, if its generalisations are of a character wholly 

 unspeculative, and bear traces of being inspired by the idealism 

 of the literature of that epoch, it was nevertheless true that 

 not only had that literary age passed away, but also the 

 empiricism in science which set aside all speculation. In the 

 same year in which the second volume of ' Cosmos ' made its 

 appearance, Helmholtz had published his treatise c Upon the 

 Conservation of Force,' which was to create a revolution in 

 science, and issue in a new epoch in the history of natural 

 philosophy. Humboldt, who was sensible of this change, 

 enters, as it were, upon a defence of his works in this intro- 

 duction. Without referring ostensibly to the new theory, he 

 makes the admission that ' though in various groups of pheno- 

 mena we are obliged to content ourselves with the discovery 

 of empirical laws, the grandest object of all scientific in- 

 vestigation unfortunately rarely attained must ever be the 

 establishment of the connection between known laws.' He 

 raises a note of warning against the c illusions ' likely to arise 

 from visionary hopes, and from < believing too hastily in the 

 discovery of the principle by which all the changes in the 

 physical world are to be explained,' while in order to reinforce 

 the warning, he brings before the reader the history of natural 

 philosophy, but in so doing he betrays a consciousness of 

 having taken up a position no longer tenable. 



This is still more evident in the introduction to the fifth 



