294 THE ISSUES OF LIFE 



Tt is clearest to start with the familiar fact of observation 

 that the life of organisms is seldom an easy affair. The 

 living creature is by its very nature insurgent and it finds 

 itself encompassed by limitations and difficulties. As Spi- 

 noza maintained, every individual thing, so far as in it lies, 

 endeavours to persist in its own being. How much more 

 a living agent, that eats into its environment, that grows 

 and stores and multiplies its kind! The vigorous creature 

 is ever hustling and jostling in its will to live. Now, as 

 every one knows, this insurgence of life meets three main 

 difficulties, and the struggle for existence in the strict sense 

 is the reacting clash. 



The first difficulty is in the tendency to over-population. 

 One weed could cover the earth in three years, one codfish 

 could soon fill up the vastness of the sea, and one fly could 

 soon shut out the sun. This tendency to overwhelming abun- 

 dance limits the foothold and food-supply of the prolific 

 organisms and of others in the same area; there are indi- 

 vidual reactions against the limitations, and these constitute 

 the struggle for existence which soon counteracts one of its 

 own causes. A second difficulty follows from the pattern of 

 the web of life, that is to say, from the nutritive inter-rela- 

 tions that have in the course of time been established. Plants 

 have banked for animals, which draw on them. The higher 

 animals devour the lower, and Nature is run on a plan of 

 successive reincarnations. This conjugation of the verb to 

 eat involves difficulties, and leads to the struggle for ex- 

 istence. A third limitation is the irregular changefulness 

 of the physical environment. 



None of the reasons which we have just recalled can be 

 said to necessitate the struggle for existence. (1) There 

 might have been a flood-bed for the teeming river of life, 



