“The only thing we have to fear is fear itself — nameless, unreasoning, unjustified terror which paralyses needed efforts to convert retreat into advance.” The words are Franklin D Roosevelt’s. His challenge was recession, not disease, but his words have a wider resonance.

Fear is dangerous. It is the enemy of reason. It suppresses balance and judgment. And it is infectious. Roosevelt thought government was doing too little. But today fear is more likely to push governments into doing too much, as democratic politicians run for cover in the face of public panic. Is the coronavirus the latest and most damaging example?

Epidemics are not new. Bubonic plague, smallpox, cholera, typhoid, meningitis, Spanish flu all took a heavy toll in their time. An earlier generation