(CNN) "Professor Stephen Hawking was a brilliant man and a mediocre student," then-President Barack Obama said to a round of laughter, "when he lost his balance and tumbled down a flight of stairs."

It was August 2009, and Hawking was in the East Room of the White House with some of the United States' most notable citizens. Although Hawking was a British citizen, the theoretical physicist -- considered by many as one of the most brilliant scientific minds in the world -- was being honored with America's highest civilian honor: the Presidential Medal of Freedom.

"Diagnosed with a rare disease and told he had just a few years to live, he chose to live with new purpose," Obama said of Hawking's ALS, or amyotrophic lateral sclerosis, which he was diagnosed with in 1963.

"From his wheelchair, he's led us on a journey to the farthest and strangest reaches of the cosmos. In so doing, he has stirred our imagination and shown us the power of the human spirit here on Earth," Obama said during the ceremony.

In honor of Hawking's 71st birthday, the Obama White House in 2013 released footage of a brief interview from his time there. Hawking said he wanted to share the excitement of discovery with everyone and that living with ALS had "not prevented me from exploring the universe with my mind."

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