Struggle for existence
"I should premise that I use the term Struggle for Existence in a large and metaphorical sense, including dependence of one being on another, and including (which is more important) not only the life of the individual, but success in leaving progeny ... a plant on the edge of a desert is said to struggle for life against the drought, though more properly it should be said to be dependent on the moisture". (p62 of the first edition)