The aim of the present thesis is to analyse the essayistic study Lacuna, Saggio sul non detto, of the Italian research scholar and professor of Italian and Comparative literature at the University of Oxford Nicola Gardini. One of the main concepts that the book revolves around is what is omitted by the authors of great fiction, such as novels, short stories and the greatest stories of the western cannon from the Greeks up to present days. In rhetoric, the linguistic tension between lacuna and a textual sense recalls the figure of the ellipsis. From a stylistic point of view, the ellipses streamline the text. At the core of the book are those particular gaps in the narrative discourse that are due to ellipses of the essential elements of the story and the plot. Lacuna is a very specific rhetorical tool and a narrative strategy, but at the same time it opens more general perspectives. The lacuna needs the readers to cooperate and to collaborate with the text in order to make sense of it. Thus the lacuna is the happy void that stimulates the reader to an experience of fullness and to collaborate logically and gnoseologicaly in making literature a complex field of knowledge.