Louis Braille certainly wasn't your average teenager. Blind from the age of four, he was only fifteen when in 1824 he invented a reading system that converted printed words into columns of raised dots. Through touch, Braille opened the world of books to the sightless, and almost two hundred years later, no one has ever improved upon his simple, brilliant idea.

Margaret Frith is the author of Who Was Thomas Alva Edison? and Who Was Franklin Roosevelt? She lives in New York City.