I think we have been fooled about what we can expect from medicine—fooled, one could say, by penicillin. Alexander Fleming’s 1928 discovery held out a beguiling vision of health care and how it would treat illness or injury in the future: a simple pill or injection would be capable of curing not just one condition but perhaps many. Penicillin, after all, seemed to be effective against an astonishing variety of previously untreatable infectious diseases. So why not a similar cure- all for the different kinds of cancer? And why not something equally simple to melt away skin burns or to reverse cardiovascular disease and strokes?

I think we have been fooled about what we can expect from medicine—fooled, one could say, by penicillin. Alexander Fleming’s 1928 discovery held out a beguiling vision of health care and how it would treat illness or injury in the future: a simple pill or injection would be capable of curing not just one condition but perhaps many. Penicillin, after all, seemed to be effective against an astonishing variety of previously untreatable infectious diseases. So why not a similar cure- all for the different kinds of cancer? And why not something equally simple to melt away skin burns or to reverse cardiovascular disease and strokes?