History of a hypothesis

The main ideas about preventing illness run through the whole of human history even if, in every age and in every place, they find new interpretation. Spanning 5,000 years, this chapter reveals prevention’s common themes, including the following: illnesses have preventable causes (Neolithic filtration and boiling of water); the choice of prevention over cure is conditional on the balance of costs and benefits, where the benefits depend on the risk, timing and severity of the hazard (shipping insurance, from 4000 BC); prevention is about improving health, not merely avoiding illness (Ancient Greece); prevention is for communal as well as personal health (Roman aqueducts and communal toilets); prevention is at a premium in the absence of a cure (fourteenth-century plague); the costs and benefits of prevention can be calculated and used to make choices about health (Franklin on fire insurance, Chadwick on sanitation); and the immediate, preventable causes of illness (diet, tobacco) depend, in turn, on deeper causes, in societies, economies and environments (Hippocrates to the Sustainable Development Goals).