 The structure of the argument of the Origin has been the topic of considerable literature and can only be summarized here  (Darwinism,  this encyclopedia; Hodge 2013b; Hoquet 2013; Waters 2003; Depew 2008; Ruse 2008; Lennox 2005). Darwin himself described his book as “one long argument”. The exact nature of this argument is, however, not immediately transparent, and alternative interpretations have been made of his reasoning and rhetorical strategies in formulating his evolutionary theory.