Cozens's famous 'blot' technique was fully evolved by the 1750s. However he did not explain it in detail until the publication of 'A New Method of Assisting the Invention in Drawing Original Compositions of Landscape'(1786). The idea seems to have originally been developed by him as a teaching aid, to liberate the imagination of the student who, he felt, spent too much time in copying the works of others. He wrote that the blot was a 'production of chance, with a small degree of design'. The true blot was 'an assemblage of accidental shapes', 'forms without lines from which ideas are presented to the mind'. Blotting was done deliberately, the 'rude forms' which result having been made 'at will'.