A typical quote used to explain the theory of evolution by natural selection is:
"Variation is a feature of natural populations and every population produces more progeny than its environment can manage. The consequences of this overproduction is that those individuals with the best genetic fitness for the environment will produce offspring that can more successfully compete in that environment. Thus the subsequent generation will have a higher representation of these offspring and the population will have evolved." - Charles Darwin
Does anyone know the exact source for this quote (i.e. where Darwin wrote or said it)?
P.S. I have tried 'On the Origin of Species' and some of his other works but I can't seem to find it.