This dissertation aims at examining the issue of the imagined book while avoiding its characterization in terms of failure, incompleteness, loss and spectre, which are prevalent in contemporary literary studies. As it approaches the diverse phenomenon of the imagined book on the basis of its deliberate articulations, instead of precluding their discussion, this study is grounded in a formal approach which endeavours to circumscribe a small genre characterized by the announcement of one or several upcoming book(s), thereby coming close to the ars poetica or the manifesto but remaining irreducible to the two genres. The term in use in book and publishing history being that of prospectus, I thus termed the genre I delineated, with a focus on its first-person, autographical form, its typically public, “serious” dimension, whether as an autonomous text or as a part of a larger body of text. The first chapter resorts to poetics, to the pragmatics of language acts and to textual genetics to offer a synchronic poetics of the prospectus and outline its formal possibilities. The following two chapters look at two historical periods: the second half of the 16th century and the early 17th century first, then the second half of the 20th century and the early 21st century. This study therefore explores the edges of the modern regime of historicity with its emphasis on the future and its promises – transition periods marked by the transformation of time imaginaries. It is also grounded in an analysis of forms and discourses. As such, it probes the social expression of a certain sense of the future, as mediated by (present and potential) writing and publishing, as well as by the dynamics of a diverse field of literature.