In 1665, a terrible sickness swept through England. It was called the plague. It caused huge swellings all over the body and made people’s skin turn black. There was no cure. Most people who caught it died a quick and painful death. Any place people lived crowded together was dangerous, because plague was very easy to catch. No one knew what caused it, or how to protect themselves against it. The only way to stay safe was to go to the countryside, where there were fewer people to catch it from.
A twenty-three-year-old student named Isaac Newton had to leave Cambridge University and flee to his mother’s farmhouse. He didn’t really mind. He had always been a loner. He didn’t have friends he would miss. At his mother’s house, he spent the time doing what he did best—thinking about the universe.
One day he saw an apple fall. He began to wonder what pulled the apple toward the Earth. And so, according to the famous legend (which might even be true), young Isaac Newton thought up the idea of gravity.
The plague years were a terrible time for most people, but not for Newton. For him, they were a wonderful time of discovery, and not just about gravity. He came up with enough new ideas to keep him busy thinking and writing for the rest of his life. His ideas helped people understand how the universe worked in a new way.
After eighteen months, Newton went back to Cambridge, but he never did make many friends. He was jealous and unfriendly, and he lost his temper easily. He wasn’t a very nice person, but he was one of the greatest scientific geniuses who has ever lived.