The French documentarian Jean Rouch (1917–2004) was one of cinema history’s most prolific, inventive, persistent, and influential kino-práxis-mensch in the eyes of fiction and documentary filmmakers, anthropologists, ethnographers, film fans, critics, and scholars alike. On December 17, 1969, Rouch met with the American Roy G. Levin (1931–2003) for an interview at the “Musée de l’Homme.” The chapter divides its reading of Rouch’s definitional exegesis into two sections. First is a hermeneutic response to Rouch’s definiens argued in the spirit of Aristotle’s “immediate definition.” Next, the chapter moves on to a close reading of Rouch’s collection of historical reflections on nine great masters of cinema, pointing at how he understands their structural contribution to the formulation of Documentary’s core. This section is treated according to what Aristotle terms “syllogistic definition.” On the whole, Rouch’s definitional gesture offers, I claim, a rare combination of the two types of Aristotelian definitions. More broadly, Rouch orients his definitional gesture according to one major principle: “subjectivity”—serving as a master key to all the documentarological doors he is about to open.