The Master and His Emissary: The Divided Brain and the Making of the Western World is a 2009 book written by psychiatrist Iain McGilchrist that deals with the specialist hemispheric functioning of the brain. The differing world views of the right and left brain have, according to the author, shaped Western culture since the time of the ancient Greek philosopher Plato, and the growing conflict between these views has implications for the way the modern world is changing. In part, McGilchrist's book, which is the product of twenty years of research, reviews the evidence of previous related research and theories, and based on this and cultural evidence, the author arrives at his own conclusions.