The influence of Leonardo was strongly felt in Milan, where he spent so many of the best years of his life and founded a School of painting. He was a close observer of the gradation and reflex of light, and was capable of giving to his discoveries a practical and aesthetic form. His strong personal character and the fascination of his genius enthralled his followers, who were satisfied to repeat his types, to perpetuate the "grey-hound eye," and to make use of his little devices. Among this group of painters may be mentioned Boltraffio, who perhaps painted the "Presumed Portrait of Lucrezia Crivelli" (Plate VII.), which is officially attributed in the Louvre to the great master himself.