Will Athens succeed? Will its fortifications manage in time to isolate Syracuse? This is the sole question that is asked and that dominates the whole account. An Athenian victory depends on entirely on the possibility of undertaking and achieving the construction of a wall; a Syracusan victory becomes simply a matter of delaying or preventing it. And this opposition gives to the text a corresponding continuity and unity and allows readers to follow step by step, in detail, the narrative progression, the unfolding of a single enterprise, a single project.