George Gemistos Plethon on God: Heterodoxy in Defense of Orthodoxy
The Emperor, John VIII Palaeologos, knew they were going to face some of the finest minds in the Roman Church on their own soil; he therefore wanted the best minds available in support of the Byzantine cause to accompany him. Consequently, the Emperor appointed George Gemistos as part of the delegation.
The Symbolical Career of Georgios Gemistos Plethon
Thus Gemistos was the first who in an authoritative way attacked the hegemony of Aristotle in western thought.