In art, conciseness is both a necessity and a luxury; a concise man provokes thought, a wordy man provokes boredom; always move towards conciseness. In the figure, look for the main light and the main shadow, the rest will come of itself: often, it amounts to very little.
Source, in full
Quote by Georges Jeanniot, Jan. 1882 - written after visiting Manet's studio; as quoted in 'The Importance of Manet's Conceptualization in 'Olympia' and 'The Bar at the Folies-Bergère', by Charles Moffat, on 'The Art History Archive', c. 2001
Notes from Wikiquote
Manet kept on working during Jeanniot's visit; he was painting 'The Bar at the Folies-Bergère'