.. there's nothing harder in the world than making art, particularly when no one understands it. Women want portraits without shadow, men want to be dressed up in their Sunday best; there's no way out. To earn money with things like that, you'd be better of walking on a treadmill. At least than you would not be abdicating your convictions.
In his letter (Paris, January 1846), as quoted in 'Gustave Courbet', by Georges Riat, Parkstone International, 2015