Giovanni Francesco Barbieri, better known as Il Guercino (“The Squinter”), was an Italian painter whose work had a profound impact on the development of 17th-century Baroque decoration. One of the outstanding draftsmen of his age, he was known for his frescoes, altarpieces, oils, and drawings. When he was 30, he was called to Rome by Pope Gregory XV and spent a productive two years there. Later, he moved to Bologna and was its leading painter until his death. How did he get his nickname? Discuss