THE RELATIVITY OF ALL KNOWLEDGE. 85 



tion, whereby more heat may be evolved; to which add, 

 that if from atmospheric changes the loss becomes greater 

 or less, the production must become greater or less. And 

 similarly throughout the organic actions in general. 



When we contemplate the lower kinds of life, we see 

 that the correspondences thus maintained are direct and sim- 

 ple; as in a plant, the vitality of which mainly consists in 

 osmotic and chemical actions responding to the co-existence 

 of light, heat, water, and carbonic acid around it. But in 

 animals, and especially in the higher orders of them, the cor- 

 respondences become extremely complex. Materials for 

 growth and repair not being, like those which plants re- 

 quire, everywhere present, but being widely dispersed and 

 under special forms, have to be found, to be secured, and to 

 be reduced to a fit state for assimilation. Hence the need 

 for locomotion; hence the need for the senses; hence the 

 need for prehensile and destructive appliances; hence the 

 need for an elaborate digestive apparatus. Observe, how- 

 ever, that these successive complications are essentially 

 nothing but aids to the maintenance of the organic balance 

 in its integrity, in opposition to those physical, chemical, 

 and other agencies which tend to overturn it. And observe, 

 moreover, that while these successive complications sub- 

 serve this fundamental adaptation of inner to outer actions, 

 they are themselves nothing else but further adapta- 

 tions of inner to outer actions. For what are those 

 movements by which a predatory creature pursues its 

 prey, or by which its prey seeks to escape, but cer- 

 tain changes in the organism fitted to meet certain 

 changes in its environment? What is that compound 

 operation which constitutes the perception of a piece 

 of food, but a particular correlation of nervous modifications, 

 answering to a particular correlation of physical properties ? 

 What is that process by which food when swallowed is re- 

 duced to a fit form for assimilation, but a set of mechanical 

 and chemical actions responding to the mechanical and 



