Pasang is forty-six, a Sherpa, and has led high-mountain treks for twenty-two years. His English vocabulary is small, but enough — most of the time he needs only one phrase: slowly, slowly.

On the first day out the clients were excited, their steps quick. Pasang walked at the front and said, without turning his head: slowly, slowly. This one was technical instruction: up here, speed is borrowed, and you repay it in the afternoon, or the next day.

On the fourth day, on a long climb, one client began to wrestle with himself, gritting his teeth to catch the people ahead. Pasang slowed and walked abreast of him, and said softly: slowly, slowly. This one was consolation: the mountain is right there; what you are chasing is not the mountain but other people — and other people are not on the itinerary.

On the seventh day, the pass. Prayer flags snapped in the wind, snow peaks stood in a ring, and the clients had all fallen silent. One man stood there a long while, and as he made ready to turn back Pasang said it a third time, beside him: slowly, slowly. This one is the hardest to translate. Something like: this moment will not come again, do not be in a hurry to leave it.

On the plane back to Kathmandu, the client who had once wrestled with himself wrote a line in his notebook and later photographed it for us: on this trip I learnt a single word, with two more layers of meaning than the dictionary gives it.

Good guides are all like this: few words, but every one of them said at the right altitude.