Whistler was one of the most original, if also tirelessly self-promoting artists of the later 19th century. After his disastrous run-in with John Ruskin, the greatest critic of the previous generation, Whistler poured his thoughts and feelings about art into this lecture, which made him if anything more notorious, but was also widely admired for its insights and wit. It is reproduced here exactly as he had it printed, with an essay by the leading scholar Margaret MacDonald putting it into the context of Whistler's career and times.