During the winter of 1844-45, Ruskin 's study of Turner 's Liber Studiorum led to a change in his own drawing technique ( Works, 35.340). He used pen work for accents and outlines, and sepia wash for light and shade, as equivalents for Turner's etched lines and mezzotint shading. From that time, he wrote, 'I understood the meaning of the words "light and shade"' ( Works, 36.131). (See Davis, The 'dark clue' and the Law of Help, pp. 33-34.)