Vincent van Gogh used art to express his intensely emotional response to the world around him. Enraptured by the beauty of nature and tormented by the sorrows of human existence, he produced in his tragically short life some of the most powerfully expressive paintings ever seen. Many have made the mistake of thinking him mad, and he did suffer throughout his life periods of mental anguish. But Van Gogh's paintings are not the works of a madman. Van...