The Master and His Emissary by Iain McGilchrist argues that the human brain's two hemispheres operate in fundamentally different ways, with the left hemisphere favouring logic, language, and analysis, and the right hemisphere favouring intuition, emotion, and wholistic understanding. McGilchrist presents evidence from neuroscience and cultural history to support his thesis, suggesting that the Western world has become excessively reliant on the left hemisphere, leading to imbalances in the way we think, perceive, and interact with the world.