Sacks explicitly states in the Preface that he wishes to “redefine the very concepts of ‘health’ and ‘disease,’ […] rather than in the terms of a rigidly defined ‘norm.’” (xvi). His professional training as a neurologist often requires strict and rigid thinking about what makes for a healthy or unhealthy—or normal or abnormal—person. Yet this training is at odds with his own experiences with his body, as his recovery from shoulder surgery demonstrates. While he is temporarily unable to use one of his arms, his brain and body find ways to adjust to this change, adapting to his new physical “normal.” While some of these changes are intentional, others he finds himself doing instinctually, his brain making adjustments without him explicitly deciding to do so.

He offers this experience in the Preface in order to remind the reader of just how much our bodies evolve, change, and adjust themselves over the course of a lifetime. Whether due to injury, disability, physical or neurological conditions, or any number of other reasons, most if not all of us will at some point have a body that does not fit into any preconceived “norm.” Rather than framing this as something negative, Sacks offers a vision of health, body, and mind that is far more expansive than the binary of healthy versus unhealthy, opening up space to consider what we might learn from patients with neurological conditions.