The nurse who made numbers impossible to ignore

Florence Nightingale knew that a table of numbers was not enough to change policy.

After the Crimean War, she studied records showing that disease killed far more soldiers than battle wounds.

She used a striking polar-area diagram to make monthly deaths visible at a glance.

The image helped persuade officials that sanitation, ventilation and clean water could save lives.

The detail changes the usual picture of Florence Nightingale. A famous life can look inevitable from a distance, but close up it is built from experiments, accidents and small decisions.

Progress often begins when clear evidence makes an invisible problem easier to see.