Giovanni Francesco Barbieri, called "Il Guercino" (the cross-eyed) because of an eye defect, was one of the most influential painters of the Italian Baroque. He trained in his rural home town and showed great talent as a painter and draughtsman at an early age. He was self-taught in his naturalistic style with subtle contrasts of light and shade. As early as 1614/15, he received his first commissions in his home town. In 1615, at the invitation of Cardinal Alessandro Ludovisi (later Pope Gregory XV), he spent some time in Bologna. While there, Guercino met the Bolognese painters from the group around Ludovico Carracci. A study trip to Venice had a decisive influence on his development as a painter and put him in contact with other influential patrons. Guercino worked mainly for the church; his frescoes and altarpieces can be seen in churches in Rome, Ferrara, Modena, Verona and Piacenza, among others. However, he also frescoed the palazzi of private patrons. During his lifetime, he was renowned internationally. Today, his paintings are on display in museums all over the world, while his numerous drawings since the 18th century are mainly to be found in English collections. Guercino's professional career is exceptionally well documented, as first his brother, then his brother-in-law, meticulously listed the earnings from the workshop in an account book.