From the book:
Chance encounters led to magic.
Frank Haven Hall, superintendent of the Braille Institution for the Education of the Blind, unveiled a new device that made plates for printing books in Braille. Previously Hall had invented a machine capable of typing in Braille, the Hall Braille Writer, which he never patented because he felt profit should not sully the cause of serving the blind. As he stood by his newest machine, a blind girl and her escort approached him. Upon learning that Hall was the man who had invented the typewriter she used so often, the girl put her arms around his neck and gave him a huge hug and kiss.
Forever afterward, whenever Hall told this story of how he met Helen Keller, tears would fill his eyes.