The Master and his Emissary: The Divided Brain and the Making of the Modern World, by Iain McGilchrist

First published in 2009, The Master and his Emissary is a landmark in studies on the two hemispheres of the brain, and how their different modes of interacting with reality have shaped the world we live in. Iain McGilchrist is a psychiatrist and academic and has been both a practising consultant and a professor of English literature at Oxford University. His comprehensive grasp of arts and science is one of the keys to the book’s success, providing not only the clinical research to back up his arguments, but also finding their expression and manifestation in the artistic achievements of the Western world.

It is a long, detailed study, not always the easiest of reads, but – not unlike the brain itself – it is made up essentially of two parts. In the first, McGilchrist defines what the differences between the two hemispheres of the brain actually are. Popularised notions from the 1960s and 70s have long been proved incorrect. It used to be thought, for example, that the left hemisphere dealt with rational thought and language, while the right was more imaginative and intuitive. Later studies showed, however, that things like language and the imagination involve both hemispheres. As a result, for some time many in the scientific world refused to take study of the brain hemispheres seriously. Thanks to this book, however, it has returned to be a matter worthy of attention.

McGilchrist noticed that differences in the brain hemispheres were observed in animals. For example, a bird picking out grains of food from the ground will focus on this particular task with its right eye – which is controlled by the left hemisphere of its brain – while the left eye, which is the concern of the right hemisphere, is generally on the lookout for what is going on around it, be it the arrival of a sudden danger or a friend. Extending his research to humans, McGilchrist found that this essential distinction could be found among us as well. In simple terms, the left brain is very good at detailed work, at categorising and ordering and at understanding mechanisms, of taking things out of context. Importantly, it sees itself as being detached from the world it observes, separated from it, so that it can manipulate it. The right brain, on the other hand, sees itself as being connected with the world around it; it understands things in their totality, sees them in their context, and grasps the meanings of metaphors and paradoxes.

A clear example of left-brain thinking can be found in patients who have suffered a stroke in the right hemisphere of the brain, meaning that the left side of their bodies is paralysed, while the left hemisphere of the brain is still intact and controls the right side of the body. People in this condition, with a functioning left brain, can be virtually unaware of their own paralysis: when asked to move their left arm, they claim they can when they clearly cannot, or state that it’s not their arm, but that of someone else. Likewise, when asked to draw a tree, they will only draw the right side of one, with no branches on the left. This indicates the nature of the left hemisphere: its inability to comprehend the whole picture, its simple denial of anything which doesn’t fit in with its views, and also its curious optimism.

McGilchrist’s point is not that one side of the brain is better than the other, but that we need both. What has happened in our society, however, is that the left brain has become dominant, when it should be the other way around. The title of the book comes from a story told by Nietzsche, about a wise king or master who discovered that to rule properly he needed an emissary to deal with more mundane, day-to-day matters. In time, the emissary decided that the king wasn’t necessary, and so he deposed him. But the emissary lacked the master’s wisdom, and so eventually the kingdom fell into ruin. In McGilchrist’s analogy, the master is the right brain, and the emissary, the left.

This brings us to the second half of the book, which delves more into literature and the arts. The central concept is that at certain times in human history (principally Western history, which is the main focus) the two halves of the brain have been more balanced. These include Greece at the time of Socrates and Plato, the Roman Empire of the Augustan era, and the Western Renaissance. In these circumstances, where there is an openness to new ideas, great strides in human civilisation have taken place. What subsequently happens, however, is that the left hemisphere of the brain slowly, as in Nietzsche’s story, begins to dominate, until we arrive to the world of today, in which it has become dangerously overbearing. This is witnessed by an emphasis on ‘virtual’ reality, a digital world built on series of zeros and ones, on over-bureaucratisation and over-specialisation, a reliance on technology and unwarranted optimism about its potential, and a degradation of common sense and more holistic thinking. The thought experiment in the conclusion, in which McGilchrist imagines a world entirely taken over by left-brain thinking, chillingly reflects much of contemporary society. The master, to use the metaphor, has been betrayed.

This is not a book to read in one sitting – the language used and the ideas expressed require time to understand and digest. But it is one of the better examples in recent years of important scientific research on the nature of reality and of ourselves finding its way through to the mainstream. Ill-defined ideas about the two hemispheres of the brain can now be replaced by more specific ones which, importantly, have a significant bearing on where we are today and where we might be heading.