 To summarize a complex issue, these Notebook reflections show Darwin proceeding through a series of stages in which he first formulated a general theory of the transformation of species from common ancestry.  He then attempted to work out a causal theory of life that would explain the tendency of life to complexify and diversify (Hodge 2013a, 2003, 1985; Sloan 1986). This causal inquiry into the underlying nature of life , and the explanation of life’s innate tendency to develop and complexify, was then replaced by a shift in focus away from inner tendencies of life. It was replaced by a concern with external forces controlling population, which was, following Thomas Malthus’s (1766–1834), assumed to expand geometrically.  This shift allowed him to develop the implications of population increase for the transformation of species.