Building on Calvino's observations on Exactitude in Six Memos for the Next Millennium, the present book elucidates on the possible definitions of exactitude, the endeavor of reaching exactitude, and the undeniable limits to the achievement of this ambitious milestone. The eighteen essays in this interdisciplinary volume show how ancient and medieval authors have been dealing with the problem of exactitude vs. inexactitude and have been able to exploit the ambiguities related to these two concepts to various ends. The articles focus on rhetoric and historiography (section I), exact sciences and technical disciplines (II), the peculiarity of quotations (III), cases of programmatic inexactitude (IV) and textual transmission (V). Several interconnected questions weave a net across the volume: to what extent is exactitude the goal in ancient and medieval texts? How can the concepts of accuracy and inaccuracy aid the reinterpretation of an already known text or fact? To what extent can certain definitions of exactitude be stretched, without turning into inexactitude? The volume presents an extensive study capable of highlighting the shrewdness and aptness of the concepts introduced by Calvino more than thirty years ago.