The background to the discovery of Lyme disease teaches a salutary lesson. The symptoms and signs of this disease had been observed by doctors for a century, particularly in the Scandinavian countries, without anybody being able to draw the right conclusions. The first patients were identified in the USA by their relatives or by themselves. Recognition of their plight by the medical profession was chiefly due to the patients' tenacity. We must remember to pay attention to what patients tell us; they may often be right, even when they seem to be wrong. Where fact and theory are incompatible, it is theory, not fact, that needs to be amended. In all likelihood, we all from time to time observe disorders in our patients that are inconsistent with established scientific models, but which we nevertheless attempt to squeeze into these models. Such an approach is not uncommon in the history of medicine. The message from Lyme calls for humility and reflexion.