Helen Adams Keller is one of the 20th century's most celebrated humanitarians. The political activist dedicated much of her adult life to fighting for labor rights, women's suffrage and advocating for people with disabilities.

The Tuscumbia, Alabama native was also an author and public speaker who travelled to over 25 different countries to deliver motivational speeches.

In 1964, she was awarded the Presidential Medal of Freedom and was entered into the National Women's Hall of Fame in 1965.

Even after her death on June 1, 1968 at the age of 87, Keller remains an icon for perseverance and overcoming adversity because since the age of 19 months, she has been deaf-blind.

Her life has been chronicled in books and movies like The Miracle Worker starring a young Patty Duke.

So how did a person with such severe disability beat all the odds and achieve so much success?

When Keller lost her ability to see and hear due to "an acute congestion of the stomach and the brain," her language skills weren't very developed so she was reduced to communicating in signs only her family understood.

All that changed in 1886,  when Anne Sullivan, a former student of the Perkins Institute for the Blind, became Keller's instructor. This marked the beginning of a 49-year-long relationship during which Keller learned how to communicate with others.

At the age of 24, Keller became the first deaf-blind person to earn a Bachelor of Arts degree and pursued her love of literature by penning a few books. Over the years, Keller developed her own ways of hearing the world and speaking with people.

A rare vintage video of Keller's impressive abilities and how she learned them have been making the rounds online and we've got a hold of it.

Click on the next page to watch how a smart Keller communicates with her instructor Anne Sullivan in an amazing clip from the 1920s.

During an era when technology and resources for people with disabilities weren't as developed as they are now, Keller's incredible accomplishments are inspirational.

The deaf-blind activist was slightly under 7 years old when Sullivan began to teach her how to communicate. She learned that people spoke with their mouths by placing her hand on their faces.

Not too long after the initial lesson, Keller developed a technique in which she places her thumb on the throat, first finger on the lips and second on the nose to feel the vibrations of the spoken words so she can repeat them.

After just 7 lessons with Sullivan, Keller was able to say the sentence "I am not dumb now," word for word.

Watch Sullivan and Keller demonstrate how the technique works below in the rare video from 1928:

Even with all of her amazing accomplishments, Keller later revealed that she still has one lifelong regret - her inability to fully master speech.

"It is not blindness or deafness that bring me my darkest hours," said Keller. "It is the acute disappointment in not being able to speak normally. Longingly I feel how much more good I could have done if I had acquired normal speech," she added.

You can watch Keller voice this regret with the help of another assistant and companion, Polly Thompson in the video below:

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