 With the ingredients of the first three chapters in place, Darwin was positioned to assemble these together in his culminating fourth chapter on natural selection. In this long discussion, Darwin develops the main exposition of his central theoretical concept. For his contemporaries and for the subsequent tradition, however, Darwin’s concept of “natural” selection was not unambiguously clear for reasons we have outlined above, and these unclarities were to be the source of several persistent lines of disagreement and controversy. It is not clear, for example, whether Darwin conceives of natural selection as an efficient or as a final cause; whether it is an emergent result of other causes; or if it is a simple description of the working together of several independent causal factors without its own causal status. Judging from the text of the Origin itself, it is difficult to verify the claim that natural selection was itself considered by Darwin to be a vera causa in Herschel’s sense. The importance of the vera causa principle for Darwin’s argument has been claimed by several scholars (Hodge 2013b; Waters 2003 [2009: 124–27]). But from textual evidence, Darwin  reserved this designation in the Origin for “community of descent”, for the causes of “ordinary generation”, or even for the mistaken beliefs of “special creationists” (Origin 1859: 159, 352, 482; Depew 2008: 243).