In this spirited volume, Oliver Sacks examines the many passions of his own life – both as a doctor engaged with the central questions of human existence, and as a polymath conversant in all the sciences. Why do humans need gardens? How, and when, does a physician tell his patient she has Alzheimer's? What is social media doing to our brains? In several of the compassionate case histories collected here, Sacks considers for the first time the enigmas of depression, psychosis, and schizophrenia, and in others he returns to conditions that have long fascinated him: Tourette’s syndrome, ageing, dementia, and hallucinations. In counterpoint to these elegant investigations of what makes us human, this volume also includes pieces that celebrate Sacks’s love of the natural world – and his last meditations on life in the twenty-first century. Everything in Its Place gives us an intimate portrait of a master writer and thinker at work.