Lodovico Antonio Muratori, in the Force of Fantasy (1745), explicitly rejects the idea of an overwhelming power of imagination to which all sorts of wonders and miracles, spells and different magical practices can be attributed. It is interesting to note that, with respect to these issues, Muratori refers to the treatise De viribus imaginationis (1608) by Thomas Fienus, who was very much engaged in the controversy against the transitive powers of the faculty of imagination, in heated controversy with the positions of Avicenna, taken in the Renaissance by authors such as Marsilio Ficino and Pietro Pomponazzi. This refusal also gave rise to the European debate on magic and superstition, carried on in eighteenth-century Italy, after Muratori, by Girolamo Tartarotti and, on various fronts, by Scipione Maffei and Gianrinaldo Carli. This contribution is intended to highlight how Fienus’ work participates in the process developed in the modern age which, starting from the questioning of the reality of magical experiences, is moving towards the complete transformation of the concept of fascination and witchcraft, now included as a result of a psychological disorder.