He solidified his place in popular culture after his book, A Brief History of Time, published in 1988, sold over 10 million copies worldwide.

Considered one of the world's most brilliant thinkers, Hawking served as a professor at the University of Cambridge and led a prolific career despite a degenerative nerve disease that bound him to a wheelchair and required that he communicate through a digital voice simulator.

From his thoughts on human nature to the power of curiosity, here are some of Stephen Hawking’s most memorable quotes.

On human nature:

"If aliens visit us, the outcome would be much as when Columbus landed in America, which didn't turn out well for the Native Americans. We only have to look at ourselves to see how intelligent life might develop into something we wouldn't want to meet."

"We are all different, but we share the same human spirit. Perhaps it's human nature that we adapt and survive."

On the pursuit of knowledge:

"Intelligence is the ability to adapt to change."

"I am just a child who has never grown up. I still keep asking these 'how' and 'why' questions. Occasionally, I find an answer."

"Remember to look up at the stars and not down at your feet. Try to make sense of what you see and wonder about what makes the universe exist. Be curious. And however difficult life may seem, there is always something you can do and succeed at."

On disability:

"My advice to other disabled people would be, concentrate on things your disability doesn't prevent you doing well, and don't regret the things it interferes with. Don't be disabled in spirit, as well as physically."

On life and death:

"I believe the simplest explanation is, there is no God. No one created the universe and no one directs our fate. This leads me to a profound realisation that there probably is no heaven and no afterlife either. We have this one life to appreciate the grand design of the universe and for that, I am extremely grateful."

"The victim should have the right to end his life, if he wants. But I think it would be a great mistake. However bad life may seem, there is always something you can do, and succeed at. While there's life, there is hope."