Principle of natural selection

Question

How did Darwin reach principle of natural selection from observation of differentiations between individuals of same species?

Answer 1

Darwin knows that in the similar species there were individuals with dissimilar features. He also realized that those differences could lead to dissimilar survival and reproduction alters for every individual. Thus he discovered the significance of environment acting upon organisms and preserving those having more beneficial features for survival and more capable to make offspring and so he explained the basis of principle of the natural selection.