It is an emotional relationship, not unlike a sexual seduction.Watching Rudi, in the house of some rich peasant on the hallowed soil of villages like Erbach or Eltville, I saw this courtship being developed as it has been practised since trade began. The other mind has to be delicately entered by the trader and then scouted, as softly as a cat moves round a mouse, to see if it contains any obstacle to agreement. This other mind is of course aware of the scouting, and can halt or reject it by a minute sign at any moment. But if no obstacle is found, no warning of rejection signalled, then this infinitely subtle exploration advances until it reaches a critical point at which “Yes” is implied because it has not been denied. The closing of the deal is then brought about by a look, a movement, a slight change in the tone of voice or some other almost subliminal scrap of body language. And it’s on.In each farm parlour I leant forward, craning to hear every word.

And yet, however hard I tried, I still could not grasp the process. Rudi and the German winegrower would talk slowly and casually about apparently haphazard things: the snow last spring, the rain that summer, the moisture or dryness of the earth. Other farmers, even local politicians, might be mentioned in an aimless way. Sometimes the two men would let fall remarks about wine prices, but always referring to some other place neither very close nor very far away And then suddenly they would be getting to their feet. Rudi would pull out a notebook and write down a few words and figures.

The farmer would leave the room, murmuring a few words to his wife in the kitchen, and return with an open bottle of his own private Spatlese.And I had missed it again. The bargain had been struck – but when and how? Afterwards, as we sipped the wine, there would be practical talk about bank accounts and deliveries. But I never picked up the critical moment, the words with which the buyer and the seller told one another that the deal was on or off (because occasionally nothing was written in the notebook and we left politely but without ceremony) or that the price was too high or too low.And in the end I understood that they never did say those words. The communication between them was not telepathic, and not even exactly wordless. Instead, both individuals were using movements, pauses, words selected for mood indication rather than “meaning”, as a single hypersensitive code. To know that code, and to be able to enter the state of super-alertness which it requires, is the ancient secret of merchants.Diplomats, or at least good ones, have that secret, too.