I tell tourists that the Old Bridge is as tall as a seven-story building and that the Neretva beneath it is cold even in August. The first I read in books, the second I heard from other people. I have checked neither. I cross the bridge four times a day, five in summer, and every time I look at the stone under my feet, at those white ridges the stonemasons left so that people would not slip. I count them while I talk. To this day I have never gotten the same number twice.

My name is Ivona, and I have worked for the Stone Path agency since I finished my history degree at the university in Mostar. The pay is not much, but in summer there are tips, and in winter I have time to read. I have been afraid of heights for as long as I can remember. Not because of some fall or accident, but just like that, the way someone is afraid of dogs or the dark: my knees go soft, my palms sweat, and the world tilts to one side. That is why I cross the bridge right down the middle, with my umbrella raised so the group can see where to go. The tourists look at the water. I look at their faces, and it seems to me that I see what they see.

Ervin stood on the parapet every morning at eleven, when I brought the first big group. He wore black swim trunks, his hair wet, a towel over his shoulder and a cap in his hand. He held the cap out toward the tourists and repeated the same sentence in four languages: thirty more euros and I jump. Until he has collected it, he stands. People stood with him, took pictures of him and waited, and my schedule came apart like wet paper. "Professor, bring them closer, I don't bite," he would call out to me. "We have lunch at half past twelve," I would answer. "The Neretva doesn't know about lunch," he would say, and hold out the cap again.

He called me Professor because in front of the group I listed the years: 1566, when the bridge was finished, 1993, when it was destroyed, 2004, when it was opened again. Once, while I was waiting for him to collect his money, he said that I knew when the bridge was built but did not know what it looked like. "I look at it every day," I said. "You look at it from the bank, like a postcard. You have never looked down from it. I see how you walk, down the middle, as if it were ice." I answered that he, for his part, knew what the bridge looked like but knew nothing about it except the price. He laughed. I thought I had won.

At the end of June I brought a group of retired teachers from Lyon. One of them, tall and loud, said in English, while Ervin stood with his cap, that he would pay double if the guide climbed up there too. The group laughed. Ervin, more as a joke than out of any malice, held out his hand to me. "Come on, Professor. Just stand next to me, you don't have to jump." People started clapping. I took two steps toward the parapet and the bridge tilted. I know it did not tilt. But I grabbed the stone, fell to my knees in the middle of the bridge in front of thirty people, and could not get up until two of the teachers lifted me under the arms.

I finished the rest of the tour as if nothing had happened. I told them about the coppersmiths, showed them where to get the best coffee in Kujundžiluk, and smiled through lunch. Only later, when the bus had left for Počitelj, did I sit down on the steps below the Tara tower, and my hands shook so badly that I could not open a bottle of water. Ervin found me there toward evening. He was in jeans and a dry T-shirt, and without the wet hair he looked older and somehow smaller. He sat down one step below me. "I didn't know," he said. "Now you know," I said. "You can tell the tourists. You'll have one more story for the cap."

He was quiet for a long time. Then he asked if I knew why he collected money before a jump. I said I knew, because he needed it. "That too," he said. "But mostly because I'm afraid. I've been jumping for thirteen years, and every time, up on the parapet, my knees shake just like yours did a little while ago. The money is an excuse to stand there longer. While I collect, the fear settles a little, and when it settles, I jump. The tourists think I'm greedy. Let them. Better that than for them to see." I looked at him and did not know what to say. For the first time someone beside me had admitted being afraid, and it was the very man I had envied every morning.

He proposed a deal. I would tell him about the bridge, since he really knew nothing about it except how to fall from it, and he would teach me height, but from below. That evening, after the last group, we went down to the rocks under the Halebija tower, where the locals swim and where tourists rarely come. From below the bridge did not frighten me. It was only an arch, white and thin, as if someone had drawn it in a single stroke. Ervin made me stand on a rock as high as a chair. Then on the wall by the river. Then on another wall, a higher one. Each time he stood below and said nothing, only waited, the way he waited with the cap.

I told him about Hajrudin, the builder, and how they say that on the day the scaffolding came down he fled the town, because he did not believe his bridge would stay standing. Ervin had not known that. He said he was glad the builder had been afraid too. He brought figs from Blagaj and cold tea in a thermos, and I brought books he did not read. One evening, when I climbed to the window at the top of the Tara tower and looked down without closing my eyes, he came down the stairs after me and kissed me on the last step, as if that too were part of the exercise.

The diving competition was on the last Saturday in July. Ervin said he would not jump if I was not watching. I said I would watch from below, from the rocks, as always. "From below you see the fall," he said. "From above you see the man." I watched him from below. He jumped beautifully and took third place, and when he surfaced he waved to the riverbank, and I waved back and knew that it was not enough for me.

On the first Tuesday in August I brought a group from Seoul, twenty-two people with sun hats and fans. I did not walk down the middle. I went up to the parapet, put my palms on the stone, warm from the sun, and looked down. The Neretva was as green as bottle glass. The swimmers on the rocks were as small as crumbs. I saw the wall I had first stood on and the rock as high as a chair, which from above looked no bigger than a matchbox. My knees were shaking. I did not move.

Ervin stood on the parapet three steps from me, cap in hand. He had already started collecting. He saw me and lowered his arm. He looked at my palms on the stone, then at my face, then at my palms again. Then he left the cap on the parapet, turned to my group and said, "No collecting today." And he jumped right away, without waiting, for the first time in thirteen summers. I watched the whole jump from above. I saw him spread his arms like a swallow, bring them together just above the water, and the Neretva take him in almost without a sound.

When he surfaced, he did not wave to the bank. He tipped his head back and searched for me on the bridge, and found me where I had never been. A woman from the group asked me in English whether he was my boyfriend. I said he was part of the tour. I picked up the empty cap from the parapet and took it with me. On the way back across the bridge I did not count the ridges. I looked down, where a wet man sat on a rock, waiting for my shift to end.