Lars Hertervig: The frenzy of light

Lars Hertervig (1830-1902) was considered to be one Norway's greatest artists before he was diagnosed with incurable insanity and pushed out into the cold. The paintings from the last 30 years of his life were considered the scribblings of a child, but subsequently turned out to bear clear similarities to styles that gained ground in Europe several decades later. Was the painter insane or just ahead of his time?