Hellen Keller and her communication system.
“It is not blindness or deafness that bring me my darkest hours,”.. “It is the acute disappointment in not being able to speak normally. Longingly I feel how much better I could have done if I had acquired normal speech. But out of this sorrowful experience, I understand more fully all human tragedies, thwarted ambitions, and the infinite capacity of hope.”
See also this video of Anne Sulliivan and Helen with some more information about her speech development.