When Breath Becomes Air

by Paul Kalanithi

The word hope first appeared in English about a thousand years ago, denoting some combination of confidence and desire. But what I desired—life—was not what I was confident about—death. When I talked about hope, then, did I really mean “Leave some room for unfounded desire?” No. Medical statistics not only describe numbers such as mean survival, they measure our confidence in our numbers, with tools like confidence levels, confidence intervals, and confidence bounds. So did I mean “Leave some room for a statistically improbable but still plausible outcome—a survival just above the measured 95 percent confidence interval?” Is that what hope was? Could we divide the curve into existential sections, from “defeated” to “pessimistic” to “realistic” to “hopeful” to “delusional”? Weren’t the numbers just the numbers? Had we all just given in to the “hope” that every patient was above average? It occurred to me that my relationship with statistics changed as soon as I became one.