From here, he also shows that evolution is the product of the interplay between sudden chance and strict certainty. For example, some deer's necks suddenly became long allowing them to eat the leaves on the top of the trees. Occurring in an environment where the lower branches have no leaves, the result is that the long-necked deer thrive and the short-necked deer are eliminated.
由此，他也提到，進化是突發的偶然性與嚴格的必然性交互作用的產物，如有些鹿的頸子突然變長，可吃到樹頂的樹葉，而環境又適巧低枝無葉，因此長頸的鹿群得以繁衍，短頸的遭到淘汰。