It can be hazardous. The bulls are semi-wild, their horns have sharp points. Sometimes there are serious injuries. These are carefully measured and catalogued in the local paper the following day. One of the most common injuries inflicted by the bulls is your cornada en el recto. (Cornada means horn injury.)
During the first day's encierro, which I missed, a Bilbao man received a cornada en el recto measuring 14cm in diameter. Beside the report was a photograph of him wearing pyjamas and giving it the thumbs up from his hospital bed.
And of course every so often somebody - usually an American tourist - gets killed.
My guide book said that if I was foolish enough to run with the bulls, I should at least walk the course beforehand to familiarise myself with it. But since arriving in Pamplona, my life was suddenly far too exciting and confusing to think about matters connected with health and safety. "If I die, I die," I can remember thinking as I danced in a bar.
At ten to eight the following morning, feeling dreadful, I was admitted onto the course for my first encierro. "If I die, I die" was my motto still, though now it was a result of crapulous depression rather than exuberance. I took up a starting position at the top of a cobbled street. The entire street was packed with would-be runners, young men mostly, the majority of them dressed in the traditional red and white of San Fermn. Spectators lined the tall wooden barriers on either side. Some middle- aged men hung precariously from the iron grilles covering the medieval windows of a seminary opposite. High above us balconies were crammed with more spectators and television camera crews. The faces of those looking down from the highest balconies were lit by early-morning sunlight.
On the stroke of eight o'clock - bang! - a maroon was let off. I nearly had a heart attack. A great cheer went up from the crowd. The gates are open! The bulls are coming out!
Then bang! another maroon exploded. They're out! They're all out and running! I stood on tiptoe and looked down the street towards the corral. I couldn't see the bulls but I could see a human tidal wave coming rapidly up the hill towards me. I thought I had a few seconds to prepare myself, but the bulls were going much faster than I imagined they would and before I knew what was happening, everyone around me had had it on their toes. And when I looked again there were six black bulls and two big brown and white steers galloping straight towards me along a medieval street barely wide enough for a moped.
In about one-tenth of a second I went from self-pitying, crapulous invalid to a serious contender for the 100m dash at the next Olympic games. It was the biggest comeback since Lazarus. I was going full pelt: my knees were coming up to my chest and my eyeballs were nearly popping out. I was going so fast I didn't have time to look behind me. But I knew that the odds in favour of my receiving a cornada en el recto, and being photographed in my pyjamas for the local paper, were shortening dramatically.
When I felt close to collapse, I dodged aside and slumped against a wall with my hands on my knees. Five of the bulls galloped on by. A sixth lost its footing on the smooth cobbles, went down and came sliding towards me on its back. As it slid towards me it was looking over its belly at me. It was looking me right in the eye. I stepped aside as it hit the wall, then I watched it scrabble back on its feet and set off in pursuit of the others.
"Holy shit!" said an aghast American tourist who also had taken refuge against the wall.
But I reckon I saw fear in that bull's eye.