In 1968, my old friend from the US art scene, Alexander Calder, visited me in Rome. I had gone there in the 1950s, when my flat in New York was torn down and my first wife left me.
As an artist, Calder was first-rate, which the world has recognised. But he was also great company: witty and playful, with a brilliant mind. One evening, we went out for dinner. I had been whitewashing my studio and had walked in the paint. When I crossed my legs, Calder took out a pencil, on impulse, and drew my portrait on one of the splattered soles, and my profile on the other. He signed each: "AC".
At the end of the meal, as we walked into the street, I decided to take them off. Calder, who was built like a bear, came after me shouting: "Put your shoes back on – it's the winter, you'll catch a cold. I'll give you another drawing!" But I didn't have far to go. I got the shoes framed eventually. They now sit on my piano and are among my most treasured possessions.
The photograph was taken decades later. It was used as the cover of a catalogue for a show I gave in the museum of Spoleto in 2006. They suggested the shoes be used for the cover, but I wanted to make the image more personal, so I photographed myself reflected in the frame's glass. As you can see, it looks as if I am behind the shoes, falling feet-first. It was a piece of luck, like so much in photography.
I would describe it as a triple mug shot, and one of the most evocative photos I have taken, capturing place, person and situation. It is biographical, too: it shows me holding a camera, with the results of what I can do with a camera. As I was taking it, I was wondering if it would work. I took it in digital, looked at it, realised it was right, and kept it.