308 LIFE OF PROFESSOR HUXLEY CHAP. XII 



Descartes' attempt to explain bodily phenomena on 

 purely physical principles ; but the Cartesian notion 

 of one controlling central mechanism had to give way 

 before the proof of varied activities residing in 

 various tissues, until the cell-theory united something 

 of either view. "The body is a machine of the 

 nature of an army, not that of a watch or of a hydraulic 

 apparatus." On this analogy, diseases are derange- 

 ments either of the physiological units of the body, 

 or of their co-ordinating machinery : and the future 

 of medicine depends on exact knowledge of these 

 derangements and of the precise alteration of the 

 conditions by the administration of drugs or other 

 treatment, which will redress those derangements 

 without disturbing the rest of the body. 



A few extracts from letters to his wife describe 

 his occupation at the Congress, which involved too 

 much " society " for his liking. 



August 4. The Congress began with, great eclat 

 yesterday, and the latter part of Paget's address was 

 particularly fine. After, there was the lunch at the 

 Pagets' with the two Royalties. After that, an address 

 by Virchow. After that, dinner at Sanderson's, with a 

 confused splutter of German to the neighbours on my 

 right. After that a tremendous soiree at South 

 Kensington, from which I escaped as soon as I could, and 

 got home at midnight. There is a confounded Lord 

 Mayor's dinner this evening (" the usual turtle and 

 speeches to the infinite bewilderment and delight of the 

 foreigners," August 6), and to-morrow a dinner at the 

 Physiological Society. But I have got off the Kew party, 

 and mean to go quietly down to the Spottiswoodes [i.e. 



