By the third round of discussion, we made a decision that called for explanation: we took the Zurich-to-Venice flight out of the itinerary and replaced it with the train. A matter of fifty minutes’ flying became eight hours.

The clients’ first reaction was understandable: had we muddled our priorities? Our reasons ran to a full page, and came down to three.

First, these eight hours are not transport but the journey itself. On the stretch over the Alps, the train passes through four seasons in a single hour: the vineyards of the lake country, spruce forest, the snow line, then the long descent into the warm colours of Italy. This is a sense of process no destination can give.

Second, the luggage is taken care of, lunch is booked at a window seat in the dining car, and a child has a whole table to draw at. Eight hours on a train are less wearing than fifty minutes’ flying with its ‘arrive two hours early at the airport’ — we have done these sums many times over.

Third, and hardest to explain: a journey needs a passage of transition. To switch from the order of the German-speaking lands to the looseness of Venice by aeroplane is to have the backdrop swapped out from under you; by train it is to watch a painting change colour by slow degrees. By the time you arrive, you are ready.

The client’s email after the return held a single line: in those eight hours the three of us talked more than in the whole of the past half year.

How much the flight refunded, no one mentioned again. Some accounts were never meant to be reckoned in minutes.