The preparations for the ‘simple life’ they lived there involved Leonie in weeks of planning. Hampers were brought up from the basement and filled with crockery and china, with feather beds and linen. City suits were laid up in mothballs; dirndls were washed, loden coats and alpen hats brought out of storage and the maids sent on by train.

And there, on a verandah overlooking the water, the Professor continued to write his book on The Evolution of the Fossil Brain, Hilda composed her papers for the Anthropological Society and Uncle Mishak fished. In the afternoons, however, pleasure erupted. Accompanied by friends, relatives and students who came to stay, they took excursions in rowing boats to uncomfortable islands or walked ecstatically across flower-filled meadows exclaiming ‘Alpenrosen!’ or ‘Enzian!’ Since a number of doctors, lawyers, theologians and string quartets also had houses along the lake, some extremely high-powered conversations often grew up between one clump of flowers and the next. Midges bit people, splinters from the bathing huts lodged in their feet, bilberries stained their teeth — and each evening they gathered to watch the sun set behind the snow-capped mountains and shriek ‘Wunderbar!’

Then on the last day of August the dirndls were put away, the hampers packed — and everyone returned to Vienna for the first night of the Burg Theatre, the opening of the Opera, and the start of the university term.

It was into this fortunate family that — when the Professor was already approaching his forties and his wife had given up hope of a child — there was born a daughter whom they called Ruth.

Delivered by Vienna’s most eminent obstetrician, her arrival brought a posse of Herr Doktors, Herr Professors, University Chancellors and Nobel Laureates to admire the baby, poke at her head with scholarly fingers and, quite frequently, quote from Goethe.

In spite of this roll call of the intelligentsia, Leonie sent for her old nurse from the Vorarlberg, who arrived with the wooden cradle that had been in the family for generations, and the baby lay under the chestnut tree in the courtyard, lulled by the sweet and foolish songs about roses and carnations and shepherds that country children drink in with their mother’s milk. And at first it seemed that Ruth might turn into just such an Austrian Wiegenkind. Her hair, when it grew at last, was the colour of sunlight; her button nose attracted freckles, she had a wide, sweet smile. But no goose girl ever clasped the sides of her cot with such fierce resolution, nor had such enquiring, life-devouring dark brown eyes.

‘A milkmaid with the eyes of Nefertiti,’ said an eminent Egyptologist who came to dinner.

She adored talking, she needed to know everything; she was an infant fixer convinced she could put the world to rights.

‘She shouldn’t know such words,’ said Leonie’s friends, shocked.

But she had to know words. She had to know everything.

The Professor, a tall grey-bearded and patriarchal figure accustomed to the adulation of his students, nevertheless took her himself through the Natural History Museum where he had his own rooms. At six she was already familiar with the travail and complications that attend the reproductive act.

‘Sex is a little bit sad, isn’t it?’ said Ruth, holding her father’s hand, surveying the bottled wind spiders who bit off their partners’ heads to make them mate faster. ‘And the poor octopus… having to hold on to a female for twenty-four hours to let the eggs go down your tentacles.’

From her unworldly Aunt Hilda, who was apt to depart for the university with her skirt on back to front, Ruth learnt the value of tolerance.

‘One must not judge other cultures by the standards of one’s own,’ said Aunt Hilda, who was writing a monograph on her beloved Mi-Mi — and Ruth quite quickly accepted the compulsion of certain tribes to consume, ritually, their grandmothers.

The research assistants and demonstrators in the university all knew her, as did the taxidermists and preparators in the museum. At eight she was judged fit to help her father sort the teeth of the fossil cave bears he had found in the Drachenhöhle caves and it was understood that when she grew up she would be his assistant, type his books and accompany him on his field work.

Her little, bald-headed Uncle Mishak, still grieving for the death of his wife, led her into a different world. Mishak had spent twenty dutiful years in the personnel department of his brother’s department store, but he was a countryman at heart and walked the city as he had walked the forests of Bohemia as a child. With Mishak, Ruth was always feeding something: a duck in the Stadtpark, a squirrel… or stroking something: a tired cab horse at the gates of the Prater, the stone toes of the god Neptune on the fountain in Schönbrunn.

And, of course, there was her mother, Leonie, endlessly throwing out her arms, hugging her, scolding her… being unbearably hurt by an acid remark from a great-aunt, banishing the aunt to outer darkness, being noisily reconciled to the same aunt with enormous bunches of flowers… Carrying Ruth off to her grandfather’s department store to equip her with sailor suits, with buckled patent leather shoes, with pleated silk dresses, then yelling at her when she came in from school.

‘Why aren’t you top in English; you let that stupid Inge beat you,’ she would cry — and then take Ruth off for consolation to Demels to eat chocolate eclairs. ‘Well, she has a nose like an anteater so why shouldn’t she be top in English,’ Leonie would conclude, but the next year she imported a Scottish governess to make sure that no one spoke better English than her Ruth.

And so the child grew; volatile, passionate and clever, recommending birth control for her grandmother’s cat, yet crying inconsolably when she was cast as an icicle instead of the Snow Queen in the Christmas play at school.

‘Doesn’t she ever stop talking?’ Leonie’s friends would ask — yet she was easily extinguished. A snub, an unkind remark, silenced her instantly.

And something else… The sound of music.

Ruth’s need for music was so much a part of her Viennese heritage that no one at first noticed how acute it was. Ever since infancy it had been almost impossible to pull her away from music-making and she had her own places, music-places, she called them, to which she gravitated like a thirsty bullock to a water hole.

There was the ground-floor window of the shabby old Hochschule für Musik where the Ziller Quartet rehearsed, and the concert hall by the fruit market — the Musikverein — where, if the janitor had been kind enough to leave the door open, one could hear the Philharmonia play. One blind fiddler of all the beggars that played in the streets would halt her, and when she listened she seemed to turn pale with concentration, as children do in sleep. Her parents were sympathetic, she had piano lessons which she enjoyed, she passed her exams, but she had a need of excellence which she herself could not provide.

So for a long time she had listened with wide eyes to the stories about her Cousin Heini in Budapest.

Heini was a scant year older than Ruth, and he was a boy in a fairy story. His mother, Leonie’s stepsister, had married a Hungarian journalist called Radek and Heini lived in a place called the Hill of the Roses high above the Danube in a yellow villa surrounded by apple trees. A Turkish pasha was buried in a tomb further down on the slope of the hill; from Radek’s balcony one could see the great river curling away towards the Hungarian plains, the graceful bridges and the spires and pinnacles of the Houses of Parliament like a palace in a dream. For in Budapest, unlike Vienna, the Danube flows through the city’s very heart.

But that wasn’t all. When he was three, Heini climbed onto his father’s piano stool.

‘It was like coming home,’ he was to tell reporters afterwards. At the age of six, he gave his first recital in the hall where Franz Liszt had played. Two years later, a professor at the Academy invited Bartók to hear him play and the great man nodded.

But in fairy stories there is always grief. When Heini was eleven, his mother died and the golden Wunderkind became almost an orphan, for his father, who edited a German language newspaper, was always working. So it was decided that Heini should continue his studies in Vienna and be prepared there for entrance to the Conservatoire. He would lodge with his teacher, an eminent Professor of Piano Studies, but his spare time would be spent with the Bergers.

Ruth never forgot the first time she saw him. She had come in from school and was hanging up her satchel when she heard the music. A slow piece, and sad, but underneath the sadness so right, so… consoled.

Her father and aunt were still at the university; her mother was in the kitchen conferring with the cook. Drawn by the music, she walked slowly through the enfilade of rooms: the dining room, the drawing room, the library — and opened the door of the study.

At first she saw only the great lid of the Bechstein like a dark sail filling the room. Then she peered round it — and saw the boy.

He had a thin face, black curls which tumbled over his forehead and large grey eyes, and when he saw her, his hands still moving over the keys, he smiled and said, ‘Hello.’

She smiled too, awed at the delight it gave her to hear this music in her own home, overwhelmed by the authority, the excellence that came from him, young as he was.

‘It’s Mozart, isn’t it?’ she said, sighing, for she knew already that there was everything in Mozart; that if you stuck to him you couldn’t go wrong. Two years earlier she had begun to attend to him in her daydreams, keeping him alive with her cookery and care long after his thirty-sixth year.