Quintilian’s Institutio oratoria, a major work in the history of the rhetoric of phantasia, emphasizes the duality inherent in the concept, conceived as a distanced and verisimilar imagination whose efficacy seems paradoxically to increase as the distance diminishes. If Quintilian, after Cicero and before Philostratus, emphasizes the need of invention in the oratory, opposing phantasia to mimesis, he also especially developed the idea that the euphantasiôtos orator imagines the events he describes as if he experienced them himself, abolishing precisely the distance that characterizes the imagination of illusion. Just as fools and dreamers – a philosophical topos included in an original rhetoric - the good speaker must delude himself in order to delude the reader. Phantasia comes close to madness, an element that clearly reflects the work of Seneca the Elder, and on which the theories of Quintilian shed light in an original manner.