"Turner and Thomson of Duddingston, whom he met at Edinburgh, belonged to the same set of artists and painters, and used to go out sketching and painting together. At the meetings of the clique Turner would constantly battle with them upon the subject of light, trying to gain from Brewster and other 'savans' information thereon; and it is supposed that the discussions contributed to form a theory which enabled him to create the varied effects he has displayed in his works. To such a height, indeed, did he carry the verbal contests that the subject, it is said, finally was prohibited; and he then became more earnest to discover what combination of colour would produce light."