Patients given a treatment containing no active ingredient often report genuine improvement, and for decades this was dismissed as imagination. Careful trials have since recorded measurable physical changes: reduced pain, altered hormone levels, shifts in brain activity. What appears to matter is not the pill itself but the expectation surrounding it — the ritual of the consultation, the confidence of the doctor, even the colour of the tablet. Strikingly, the effect persists in some trials where patients are told openly that what they are taking is a placebo. Yet placebos do not shrink tumours or clear infections; they act on how symptoms are experienced, not on the underlying disease.