Celebrated theoretical physicist Stephen Hawking, known for his ideas about black holes and quantum gravity, died on Wednesday. He was 76.

Life of Hawking has been inspiration not only for generations of physicists but also for people in general. For a greater part of life he was confined to a wheelchair because of a motor-neuron disease called amyotrophic lateral sclerosis (ALS). Since 1985 he had to speak through a computer system, which he used to operate with his cheek.

In spite of his ailment with which he was diagnosed shortly after his 21st birthday in 1963 and being wheelchair-bound and dependent on the computerised voice system for communication, Hawking for more than five decades continued with his research into theoretical physics, apart from travel and public lectures.

He earned more than dozen honorary degrees in his lifetime and had authored best-sellers like ‘Black Holes and Baby Universes and Other Essays’, ‘The Universe in a Nutshell’, ‘The Grand Design and My Brief History’ and above all ‘A Brief History of Time’ that appeared on the British Sunday Times best-seller list for a record-breaking 237 weeks.
 
Here are some memorable quotes from the great ‘physicist-philosopher’

* However difficult life may seem, there is always something you can do and succeed at.

* 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.

* 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.

* People won't have time for you if you are always angry or complaining.

* Intelligence is the ability to adapt to change.

* Life would be tragic if it weren't funny.

* The past, like the future, is indefinite and exists only as a spectrum of possibilities.

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

* Keeping an active mind has been vital to my survival, as has been maintaining a sense of humour.