The two frescoes of the life of Isaac ("Isaac blesses Jacob" and "Esau in front of Isaac") in the middle register of the third bay, are traditionally ascribed to the young Giotto (1290–1295) (previously wrongly ascribed to Cimabue by Vasari). But even this has been controversial. Many critics esteem these the work of the anonymous Isaac Master and his workshop. Deducing from stylistic details, attesting to his Roman background, some think that the Isaac Master may have been Pietro Cavallini or a follower. Pietro Cavallini had painted around 1290 a similar fresco "Isaac blessing Jacob" in the convent of the church Santa Cecilia in Trastevere in Rome. The position of the resting Isaac looks like the same position of the Virgin in Cavallini's mosaic "Birth of the Virgin" in the apse of the church Santa Maria in Trastevere in Rome. The Isaac Master is considered one of the first practitioners of the true fresco ("buon fresco") technique, which revolutionized mural painting for the subsequent centuries.