Giovanni Francesco Barbieri, ‘Il Guercino’ (1591 – 1666): A Master of Dramatic Light and Emotion Giovanni Francesco Barbieri, universally known as Il Guercino—a nickname derived from the “squinter” or squint referring to his distinctive eye condition—stands as a pivotal figure in the transition between Mannerism and Baroque painting. Born in Cento, near Bologna, in 1591, his life was one of relentless artistic exploration, marked by b…