On Wednesday night, Stephen Hawking was centre stage at the Olympics stadium, exhorting the world to "be curious" during a Paralympics opening ceremony that celebrated both the achievements of science and the human spirit.
Yesterday, more prosaically, he was back at work. Despite turning 70 this year the renowned physicist continues to keep a packed diary; no sooner had he finished entertaining the crowds in Stratford than he was on his way to Cambridge.
"He travelled back that night and was in his office this morning," Tim Holt, head of media at Cambridge University, told The Independent yesterday. "Stephen is limited in what engagements he can accept because of both the pressures of work and his severe physical limitations but this was something he really wanted to do. He has a great sense of humour and this was an opportunity to showcase the importance of science and discovery."
Jenny Sealey and Bradley Hemmings, the two directors behind Wednesday night's spectacle, were determined from the outset to pay tribute to the contributions that science has made to the able bodied and impaired alike. They first approached Professor Hawking late last year to discuss whether he would be willing to make an appearance.
His involvement in such a massive production is no mean feat. Diagnosed with amyotrophic lateral sclerosis at the age of 21, Professor Hawking has been trapped in his own body for much of his adult life. For the last two decades he has only been able to communicate by twitching his cheek muscle to write words that are then relayed by his famous voice synthesiser. Composing a single sentence can take as much as 10 minutes but he was determined to write his own part. Organisers were braced for him having to pull out when he was unable to attend his 70th birthday earlier this year due to ill health but he was determined to make it. Friends and family were sworn to secrecy to keep his staring role under wraps.
Professor Hawking said he was honoured to be able to take part: "To use this stage to show the world that regardless of differences between individuals, there is something that everyone is good at, is very important."
Those who worked with him in rehearsals say they were captivated by his wit. "Everybody knows about Professor Hawking and his extraordinary theoretical work and his extraordinary writings on science which made very complex ideas accessible to all of us," Mr Hemmings said. "What came through from our meetings with him is the humanity and humour of Professor Hawking. He's a fun guy."
* The Opening Ceremony may not have attained the 27 million viewers who watched Danny Boyle's Olympic spectacular, but Channel 4 will regard its audience of 11.2 million people as a triumph.