Home » Posts tagged 'Calcidius'
Tag Archives: Calcidius
Demons, Calcidius and Vitello at ISNS Symposium
On June 3rd-6th in Leuven, Belgium, the 23rd annual symposium of the International Society for Neoplatonic Studies (ISNS) took place. The programme of the whole event can be downloaded here. AΦR was certainly present there.
Together with two other panelists, Tomasz Mróz presented his paper in the panel: Medieval Platonism. These panelists were Heide König (LMU Munich) and Ernesto Fuentes Padgett (Notre Dame). Mróz’s paper was titled Vitello’s Theory of Daemons. Platonic Inspirations in a Naturalistic Treatment.
Vitello was a philosopher and a natural scientist of the second half of the 13th century, best known for his treatise in optics. To obtain degrees he travelled to the universities in Paris and Padua, but he also visited Viterbo. Although he gained recognition as the author of Perspectiva, dedicated to Wilhelm of Moerbecke, his interests went beyond optical issues and in a letter titled De causa primaria paenitentiae in hominibus et de natura daemonum he differentiated between the real demons as animals and apparent demons, as the effects of optical illusions or malfunctions of human cognition. He developed a theory of demons, their nature, their position among natural creatures, and investigated a number of detailed issues connected to the life of demons and their various interactions with human beings.
Mróz took an attempt to demonstrate how Vitello started with Plato, Calcidius’ commentary to the Timaeus, mathematical considerations and the Averroists’ theory of double truth to prove the existence of demons as animals and how, subsequently, he took advantage of his experience as a natural scientist and a confessor to supplement the theory with a number of observations and the then common opinions that eventually, in his eyes, reinforced the theory.
The conference in Leuven was, as all ISNS events, a successful meeting, gathering specialist in history of philosophy from antiquity to modern times. It was also an opportunity to see and listen to papers of scholars from all the continents. It was also a pleasure to see there our collaborator from Vilnius University, Jonas Čiurlionis, who delivered a paper Mathematics of Music in Timaeus’ creation of the World Soul.
How to Scare International Students with Vitello’s Theory of Demons
In March (23rd-27th) 2026, an Erasmus+ Blended Intensive Programme meeting was held at the University of Zielona Góra. About fifty students representing partner universities from Bulgaria, Croatia, Czechia, Lithuania, Portugal, Romania, Turkey and Vietnam took part in this event. Ancient Φilosophy Reception research group was present there and it was Tomasz Mróz whose presentation inaugurated on-site and offline part of the whole event.
The general topic of this BIP meeting was: Interference Patterns – Science and Culture in Dialogue. Mróz’s lecture – The Philosopher Vitello of Legnica and His Scholarly Theory of Demons – aimed to demonstrate how this 13th century scientist and philosopher, man of the world and a locally engaged scholar, used ancient thinkers (Calcidius and Aristotle) and combined mathematical calculations, natural sciences, philosophy and his own life experience to develop a theory of demons as animals composed mainly of air, the subtle element. He rejected theological concept of demons as a fallen angels and took an attempt to explain various “demonic” phaenomena secundum viam naturalem et possibilem.
The questions from the audience concerned the problem of Vitello’s method as he departed from theological discourse. The discussion that followed emphasised the convergence of methods of Latin Averroists and Vitello, whose intention may have also been the defence of the autonomous character of philosophy and sciences. Feedback from students was also invaluable as they were surprised that such intriguing topics can be found in (otherwise dull?) history of medieval philosophy. Thank you Moldovan students in Romania!
As a digression in the course of the lecture, Woody Allen’s Everything You Always Wanted to Know About Sex* (*But Were Afraid to Ask appeared. However, since the episode with Daisy, the sheep, is definitely not suitable for all audiences, it will not be developed here 😉
Of course, no one would probably argue today for topicality of Vitello’s theory of demons, but at least some of his considerations should be taken as a serious piece of advice even in the 21st century: if you see demons or angels or hear them talking to you or making sounds, you should immediately consult a doctor!
Thanks to Sylwia Kondej and Magdalena Pokrzyńska
for organising such a great event!
Recent commentaries