It is well known, for example, that Newton solved many of his toughest problems when his attention was waylaid by private musings. Thomas Alva Edison also knew the value of "half waking" states. Whenever confronted with a task which seemed too hard to be dealt with, he would stretch out on his laboratory sofa and let fantasies flood his mind. Painters, writers, and composers also have drawn heavily on their sensitivity to inner fantasies. Debussy used to gaze at the River Seine and the golden reflections of the setting sun to establish an atmosphere for creativity. Brahms found that ideas came effortless only when he approached a state of deep daydreaming. And Cesar Frank is said to have walked around with a dreamlike gaze while composing, seemingly totally unaware of his surroundings.