Professor Stephen Hawking was one of the most brilliant scientists of his, or any other, generation.
But it was his ability to explain the most complex of ideas in terms that anyone could understand that brought fame far beyond the scientific community.
The renowned physicist died on Wednesday in Cambridge at age 76.
Published in 1988, A Brief History Of Time became a huge hit, selling 10 million copies and being translated into 35 languages.
Aimed at a non-scientific audience it attempted to explain some fundamental principles of physics and answer some of the oldest questions of mankind; how, why and where the universe began, how it works and where it will end.
In a simple, elegant style it covered the nature of time, gravity, black holes, the Big Bang and the physicist’s holy grail – “the theory of everything” an all-encompassing, coherent theoretical framework of physics that fully explains and links together all physical aspects of the universe.
“My original aim was to write a book that would sell on airport bookstalls,” he said at the time.
“In order to make sure it was understandable I tried the book out on my nurses. I think they understood most of it.”
The Theory Of Everything became the title of the 2014 film that charted Prof Hawking’s early life and how he came to terms with motor neurone disease, the crippling disease that gradually paralysed him.
He was confined for most of his life to a wheelchair. As his condition worsened, he had to resort to speaking through a voice synthesiser and communicating by moving his eyebrows.
His popularity brought him guest appearances in TV shows such as The Simpsons and the Big Bang Theory, but he was above all a true scientific genius.
Building on the work of scientists such as Einstein he defined and refined our understanding of the Big Bang, gravity black holes, entropy, general relativity and quantum theory.
Stephen William Hawking was born in Oxford on 8 January 1942, the eldest of four children.
The family’s home was in north London but his mother lived in Oxford because London was being bombed during the Second World War.
He was given a scholarship to study at University College, Oxford, where he studied natural sciences.
Prof Hawking’s father was a doctor of tropical medicine and wanted his son to follow him into the profession – but he wanted to be a mathematician so natural sciences was an agreed compromise.
Prof Hawking contracted motor neurone disease, also known as amyotrophic lateral sclerosis, in 1963 at the age of 21.
In his 2013 memoir My Brief History, he recalled: “At the time, I thought my life was over and that I would never realise the potential I felt I had.
“But now, 50 years later, I can be quietly satisfied with my life.”
Doctors gave him just two years to live after his diagnosis, but he went on to study cosmology at Cambridge.
He was given more than a dozen honorary degrees and was awarded the CBE in 1982.
Prof Hawking was twice married and divorced.
He married undergraduate Jane Wilde in July 1965 and the couple had three children, Robert, Lucy and Timothy.
The pair divorced in 1990, and in 1995 he married Elaine Mason, a nurse whose ex-husband had designed the electronic voice synthesiser that allowed Prof Hawking to communicate.
For him, the search was almost a religious quest – he said finding a “theory of everything” would allow mankind to “know the mind of God.”
“A complete, consistent unified theory is only the first step: our goal is a complete understanding of the events around us, and of our own existence,” he wrote.