WEIMAR AND JENA. 185 



principle of life which is wholly irrefutable ; I set great store by 

 it, and think I shall now be able to upset the old definitions.' 

 These new views rapidly gained in strength. On February 9, 

 1796, he wrote again to the same friend : 6 1 expect very soon 

 to be able to cut the gordian knot of the processes of life. . . . 

 These are the principles of my new physiology.' In December 

 of that year he sent to Van Mons a treatise entitled ' Sur le 

 Procede chimique de la Vitalite,' and in 1797 he made the 

 following statement in his celebrated work, 'Experiments upon 

 the Excitability of the Nerves and Muscles ' : 4 After much 

 thought and continued study of the laws of physiology and 

 chemistry, my former belief in any actual principle of life, as it 

 is called, has been completely shaken. I no longer view that as 

 an independent power which is perhaps only the joint action 

 of individual well-known substances and their material forces. 

 The difficulty of tracing back the phenomena of organic life to 

 the laws of physics and chemistry lies mainly, as in the case of 

 predicting the meteorological changes in the atmosphere, in 

 the fact that the complication of phenomena and the multitude 

 of forces simultaneously at work are necessary conditions of 



activity -' S 



Subsequently, however, he also renounced this view: 'I call 

 those bodies inorganic in which the particles are commingle^ *\,j 

 according to the laws of chemical affinity, and those bodies 

 organic the particles of which, upon forcible separation, change 

 their form of combination without any alteration in their 

 external conditions. There is some hidden law, therefore, 

 controlling all the particles of an organism ; the law is only in 

 force so long as all the particles are in mutual operation as a 

 means and an end to the whole. Whether tnis definition may 

 ever be made available is another question.' 1 



Thus the dream of symbolic myths and poetic allegories 

 vanished before the efforts of science to solve the problems of 

 nature. The province ascribed to the principle of life to that 

 ' common jade,' as Du Bois-Eeymond terms it became increas- 

 ingly circumscribed, till in the present state of science the very 

 expression has -become distasteful. 



1 ' Briefwechsel und Gesprache Alexander von Humboldt's mit einem 

 juugen Freunde ' (Berlin, 1861), p. 35. 



