The American brain scientist Eric Kandel won a Nobel Prize in 2000 for his life’s work on a rather unpromising item of marine life – a sea-slug called Aplysia, which possesses unusually large nerve cells (or neurons), visible to the naked eye. Kandel hoped to observe the learning response in a small group of cells involved in the slug’s breathing equipment, or gills, and the animal’s reaction to danger. If the sensory neurons detect an unfamiliar stimulus they instruct six motor neurons to ‘fire’, making the muscles around the gill pull safely back from the surface of the slug for protection. Kandel’s research revealed that as the Aplysia repeatedly avoided dangerous stimuli the nervous system changed, improving the ‘firing’ connections and the slug’s ability to survive. Kandel’s work, along with the research of many other neuroscientists over the past fifty years, has shown that experiences make crucial and actual changes in the nervous system and the brain. We become our experiences. Neuroscience shows that the brain is not a set of hardwired connections, but that it has ‘plasticity’: it is living, dynamic, and subject to constant alteration. This, according to Norman Doidge, an American psychiatrist and author, has far-reaching consequences for everything – from education to psychotherapy – and flies in the face of many entrenched assumptions.

One of the most confirmed prejudices of Western culture, as Doidge acknowledges, is the thinking of René Descartes. The French seventeenth-century philosopher believed there was a strict and technical division between the physical brain and the mind. All the interesting mental activities – will, imagination, thought – he saw as