"Sure."
The story of John Snow deserves a more serious tone. He starts with his parents recognizing his intelligence and paying for him to be sent to school. He challenged conventional wisdom and asked strange questions. He was one of the brightest in the school and was chosen for a doctor's apprenticeship soon after. But around this time the horrible specter of Cholera swept through the coal-mine slums, when he was not even yet a proper adult, only eighteen - younger than Mahan himself!
Cholera is a horrible and above all disturbingly fast disease. While not always lethal, it appeared utterly random to doctors at the time, and was terrifying. They did not understand bacteria or viruses - it was before modern medical science. John Snow tried all the treatments known to medicine at the time, but could do nothing more than ease the suffering of some of the disease's victims. But he tried his best, even in the waste and death-filled slums, suffering all around him.
The epidemic passed and John Snow moved on to other things... But he would always remember the horror of Cholera, and hate it with all his soul.
He had a promising career in medicine after that, graduating from a prestigious medical school, making breakthroughs with anesthesia, and even treating the Queen of the whole country himself. He was one of the best and brightest of the field.
When John Snow was 35, Cholera returned. John Snow still could not treat the disease any better than the other doctors, but he was determined to end the outbreak. He had an inkling by now, from watching the way things worked, that diseases are spread - but this idea was dismissed as nonsense by other doctors at the time. Still, he raced around London, tracking down relatives of the dead and the doctors who treated them, trying to gather as much information as he could. He saw how people who drank from wells that sewage drained into got sick, and those who drank from clean wells were fine, and came up with the (correct) theory that contaminated waste getting into the water was spreading the disease... But other doctors and the general public still dismissed this as nonsense, and the outbreak ended.
And then, the third devastating outbreak. This time, John Snow would not let Cholera win. Without magic, without enough money or helpers, with only his own cleverness and logic to help him, he was still determined to root out the cause and prevent future outbreaks once and for all. This time, the ravages of the disease were worse than ever. Dozens dead every day, and thousands suffering terribly. He frantically gathered testimony and data, trying to find something, anything that could be a pattern, and basically invented epidemiology overnight, using maps and logical analysis and everything else he could, to find out that... The Broad Street well was causing Cholera. Almost anyone who drank from it fell ill, and those who avoided it were shown remarkable clemency. He raced through the slums, to landlords' houses asking questions about water companies of all things, surely seeming mad, and even into the halls of the government, demanding the records that would show everyone the incontrovertible truth he had uncovered.
After all this time and effort and desperate cleverness, John Snow showed his results to the special committee organized to investigate the outbreak, and they said... 'Huh, I think you're on to something.' They removed the pump from the Broad Street well, and the great outbreak stopped, almost overnight.
John Snow was right all along. Though the medical minds of the time still didn't understand bacteria, exactly, they at least learned the lesson of sanitation. Less than a decade later, at John Snow's urging, the great city London spent tens of millions of rings to start building a proper sewer system. The grim reaper Cholera returned to London only once more, in an area where the sewers were not finished, and was quickly attacked and driven out.
"John Snow was the first. Without magic, without the support of his peers, without any money or thanks, he solved the disease. Some estimates say that John Snow's discoveries and the improvements they led to have saved hundreds of millions of lives. He is counted among the great men of my world. John Snow, Edward Jenner, Louis Pasteur, Jonas Salk, Norman Borlaug, Ronald Ross, Alexander Fleming. I have the highest esteem for experimenters like those, whose drive to understand led to so many good things."