Devastating epidemics of untreatable smallpox caused not only deaths but dire disfigurements of face and body as well as one third of all blindness. In the 20th century mortality was estimated at 300 million up to 1978, the year it was proclaimed to be eradicated. Historically, the fact has been overlooked, often forgotten, that the preventative practice of variolation for smallpox was widely adopted internationally during the 18th century and was the precursor to refinement as cowpox vaccination. Never previously traced was the extensive global adoption of the technique or the impetus for...