Chapter 3 introduces the mechanism Natural Selection uses to create new species and that is the Struggle for Existence among organisms.

The accumulation of slight but useful variation forced by the struggle for life create the emergent property of Natural Selection.

Drawing was trying to get a head of all the pseudo philosophy that would emerge due to the term "Survival of the Fittest" and the "Struggle for Existence".

Darwin notes here that the goal of life is maximum expansion. The "utmost increase in numbers".

Climate is one of the main things that indirectly affect species, because it controls the availability of food sources for many different species.

Darwin mentions that one of the tools a species has in order to protect itself from the struggle of existence is just being part of a large stock.

Darwin uses this example to show how interconnected the existence of different species is.

The last sentence of this chapter mentions the sheer number of deaths that happen in the Struggle for Existence, not just individuals by whole species.