With the death of historian David Cesarani, the world has lost a great intellectual and humanist — and I have lost my best friend.

Tributes to David continue to pour in. His obituary in the Times of London provides and good summation of his extraordinary life and achievements. But I want to write about the David I knew, a man I came to love like a brother.

I first met David in 1977 when I was the Field Worker for the Union of Jewish Students in Britain and David was elected as the head of its Midland region. We were fighting attempts on British campuses to ban pro-Israel activity as racist and I remember David and I attended one particularly scary debate at the University of Essex.

As I stepped forward to speak, extreme left-wing students, many belonging to radical Trotskyite groups, began stomping their feet, chanting anti-Israel slogans and yelling insults and threats. I stood my ground – and David stood right beside me.

That baptism by fire solidified what became a lifelong friendship — and I think it also instilled in both of us the courage to stand up for what we believed, no matter how unpopular. Indeed, David loved to provoke his audiences, whether at public lectures or in small groups around a dinner table. He never accepted conventional wisdoms and would invariably put forward arguments that seemed, on their face, to be absurd — but when you thought about them, you found yourself examining the issue with new eyes.

You always knew when one of these off-the-wall Cesarani zingers was coming. His face would take on a look of almost furtive delight because he knew he was about to shake your lazy assumptions yet again. When he spoke at a panel on anti-Semitism that I organized last spring, David followed three rather boring presentations. From the moment he opened his mouth, the audience woke up. Soon, they were gasping at his audacity and then, despite the seriousness of the issue, laughing out loud. David was always witty and could be really funny. But he was never, ever boring.

David liked to pose as a cantankerous old man — but it was just a pose. We shared a love of running, climbing mountains and attending classical concerts — and we did all three together often.

As a friend, David was loyal, loving, supportive and just plain fun to be with. We celebrated my 60th birthday with a long weekend with our wives in Amsterdam. It was a weekend of art, great food and driving wind and rain — unforgettable. I was looking forward to helping him celebrate his own 60th birthday in similar style — but he never made it.

In our final email exchanges, before and after his cancer surgery, we exchanged tips on pain management. (I underwent my own surgery some years ago.) I favored listening to classical music on my iPod which worked better than painkillers — but David said he’d been listening to BBC plays by ancient Greeks which invariably sent him off to sleep. I offered to say misheberach prayers for him and David accepted. “I am a faint-hearted agnostic and I dislike organized religion but I think we need all the help we can get,” he wrote.

The news that he had died unexpectedly on Sunday came as a massive blow. His passing leaves a hole in my life that can never be filled. I’m going to miss David for the rest of my life — but I’m honored to have known him and to have enjoyed his friendship.