The Liber Studiorum is a series of engravings which were published by Turner in parts between 1807 and 1819. Each part consisted of five plates, printed in brown ink and sewn in a paper wrapper. Each plate carried an etched outline, usually etched by Turner himself, with light and shade expressed by mezzotint engraving. The mezzotint was usually added by an engraver under Turner's supervision, but in a few cases it was done by Turner himself. Turner drew the series to a close prematurely, with a total of 71 plates issued. The meaning of the Liber Studiorum has been a matter of much debate.
Ruskin makes many references to the Liber Studiorum in Modern Painters I, but these were all added in 1846, for the third edition. It seems likely that Ruskin's introduction to the Liber Studiorum did not occur until late in 1843, after publication of the first edition of Modern Painters I. The importance of the Liber Studiorum for Ruskin was considerable, and the engravings remained a major influence throughout Ruskin's life (see Davis, The 'dark clue' and the Law of Help).