 For Aristotle, an individual life begins when the male and female semen are brought together. This is an external action, which starts the individual formative process. From that point on, the process is internal, initially driven by causes internal to the combined fluids. The process then leads to formation of the individual’s type, since “once a thing has been formed, it must of necessity grow” (Aristotle GA 1.735a18–19). (See Lennox 2001 for discussion of Aristotle’s predecessors on these points; see Van Speybroeck et al. 2002; Vinci &amp; Robert 2005; Connell 2016, 2020; Falcon &amp; Lefebvre 2017; Henry 2017; Hopwood et al. 2018; on Aristotle’s theory of generation and subsequent scientific development of these ideas.)