Central to this book is a trio of chapters (4, 5 and 6) on Darwin’s Origin of Species in its first edition of 1859. Darwin called his book 'one long argument'. These three chapters clarify how this long argument is conducted; how Darwin’s analogical reasonings about natural and artificial selection support the argument; and how his various metaphors are grounded in those reasonings. The conclusions from these chapters support the claims in our chapters 1 to 3 about the decisive antecedents, from ancient times on, for Darwin’s conception of analogical reasoning and what it can do for his one long argument. Equally these conclusions support the claims made in our chapters 7and 8 as to how that reasoning should be analysed and evaluated by philosophers, biologists and historians today. Our writing combines throughout narratives that are often not overtly normative with judgements that often are so.