Giorgio Vasari, Lives of the Most Excellent Painters… (1850)
“ Thus, we have certainly great obligations to Stefano, for he who, walking in darkness, encourages others by showing them the way, confers the benefit of making known the dangerous points, and warning from the false road, enables those who come after to arrive in time at the desired goal. This master also began to paint in fresco the chapel of Santa Caterina, in the church of San Domenico, in Perugia, but left it unfinished. At the same time with Stefano, there flourished the Sienese painter Ugolino, his intimate friend, and who also enjoyed considerable reputation. ”
