Vasari characterizes Paolo Uccello as an eccentric melancholic. He enjoyed painting animals, especially birds, which earned him his nickname (uccello = bird), and he was so in love with perspective that he spent entire nights with it. Piero della Francesca is regarded by Vasari as the virtuous master of perspective. He was betrayed by a student who wanted to erase the memory of Piero. However, Vasari claims to have saved the painter's memory by writing his biography. Regarding Antonello da Messina, the great portraitist of the Renaissance, Vasari writes that he learned his detailed painting technique from the van Eyck brothers. He earned great merit in spreading oil painting in Italy. Luca Signorelli focused primarily on the perspective view of naked bodies, as shown in his fresco The Damned in the cathedral of Orvieto.