We always knew when Stephen was coming to dinner. It was 1966, my first year studying mathematics at Cambridge, and I happened to be in the same college as Stephen - Gonville and Caius, College. One of the prescribed parts of college life was dining together. We all sat on long tables in the Great Hall, while the college fellows sat on high table across the end. Think Harry Potter and you've got a pretty good picture. Once we'd all assembled the head-waiter would ring the large gong, read a Latin grace, and dinner would be served.
But some days, after all the fellows had filed in, the gong would remain silent. That's when we knew Stephen was coming to dinner. We all waited, and after a while Stephen would shuffle in on a walking stick and take his seat at high table. And grace would be read.
He was the youngest person to be elected a Fellow of the college - only four years older than myself. He had just completed his doctoral work on black holes, and was recognized back then to have a brilliant mind. He'd been diagnosed with Lou Gehrig's disease a couple of year's earlier. At the time it was thought he only had a few years to live. It later turned out that his particular form need not be terminal.
Two year's later I had the good fortune to have Stephen assigned as my supervisor. Each week I had an hour's personal meeting with him, when he would set me problems to solve over the coming week - and usually explain where I had gone wrong with the preceding week's problem. He could still talk with his own voice then, although it was a whispery hiss; and he could still walk, leaning against the walls of the mathematics department for support as he made his way to his office.
What I remember most of all about these times with him is that he never let his condition get to him. One day a muscle jerk in his arm pushed a pile of papers full of equations in his large handwriting across the table and on to the floor. I stooped to pick them up for him, but he wouldn't let me saying he'd do it later - even though it would undoubtedly take a lot more time and effort than my doing so. Nor did his sense of humour leave him, a wry smile often creeping across his face as he attempted to explain some subtle implication of an equation.
He died on Einstein’s birthday, and was born the day Galileo died. Rather fitting considering that Galileo formulated the classical theory of relativity, Einstein extended it to Special and then General Relativity, and Hawking built on General Relativity in his seminal work on black holes.