Eric Frank Russell

Only the strong know there is but one cause of war. All the other multitudinous reasons recorded in the history books were not real reasons at all. They were nothing but plausible pretexts. There was but one root-​cause that persisted right back to the dim days of the jungle. When two monkeys want the same banana, that is war.

Eric Frank Russell, ”I Am Nothing,” Astounding Science Fiction (July 1952).