On not giving up:“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. It matters that you don’t just give up.” Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings. On God:”It is not necessary to invoke God to light the blue touch paper and set the universe going” – The Grand Design, published 2010.On commercial success:”I want my books sold on airport bookstalls” – Interview in The New York Times, December 2004.On fame:”The downside of my celebrity is that I cannot go anywhere in the world without being recognised. It is not enough for me to wear dark sunglasses and a wig. The wheelchair gives me away” – Interview on Israeli TV, December 2006.On an imperfect world:”Without imperfection, you or I would not exist” – In Into The Universe With Stephen Hawking, The Discovery Channel, 2010.On euthanasia:”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” – Quoted in People’s Daily Online, June 2006. On the importance of having a sense of humour:”Life would be tragic if it weren’t funny” – Interview in The New York Times, December 2004.On death:”I have lived with the prospect of an early death for the last 49 years. I’m not afraid of death, but I’m in no hurry to die. I have so much I want to do first” – Interview in The Guardian, May 2011. On intellectual showboating:”People who boast about their IQ are losers” – Interview in The New York Times, December 2004.On the possibility of contact between humans and aliens:”I think it would be a disaster. The extraterrestrials would probably be far in advance of us. The history of advanced races meeting more primitive people on this planet is not very happy, and they were the same species. I think we should keep our heads low” – In Naked Science: Alien Contact, The National Geographic Channel, 2004. Stephen Hawking captured the public’s imagination as a trapped mind exploring the boundaries of scientific knowledge. Here are some memorable pearls of wisdom from one of the world’s most famous scientists:On the reason why the universe exists:”If we find the answer to that, it would be the ultimate triumph of human reason – for then we would know the mind of God” – A Brief History Of Time, published 1988.On being diagnosed with motor neurone disease:”My expectations were reduced to zero when I was 21. Everything since then has been a bonus” – Interview in The New York Times, December 2004.On black holes:”Einstein was wrong when he said, ‘God does not play dice’. Consideration of black holes suggests, not only that God does play dice, but that he sometimes confuses us by throwing them where they can’t be seen” – The Nature Of Space And Time, published 1996.