Most violinists, when they essay playing the viola, have to use a smallish instrument and hence produce a modest tone. Busch was big enough in physique and had a sufficiently wide hand-stretch to manage quite a large viola, such as the ‘Paganini’ Strad on which he several times performed Harold in Italy. Another viola he occasionally played was the bastard instrument, owned by the Viennese collector Wilhelm Kux, which had begun life in 1715 as a Stradivari viola d’amore. Throughout his career, he owned violas: his father made him at least two; his father-in-law Hugo Gruters gave him one; he acquired an excellent 1783 Giovanni Battista Guadagnini; and in 1934 he bought Dea Gombrich a Vincenzo Panormo for ￡103. That year Fritz Baumgartner built him an instrument to order. He even kept a viola pomposa, constructed by Wilhelm Busch, and played it occasionally. His training at the Cologne Conservatory included a certain amount of viola-playing; and he appeared several times as violist of the Gurzenich Quartet. But those were the days when German orchestral musicians called the Bratsche the ‘Penzioninstrument’, as William Primrose pointed out:

Busch shared this rather denigratory view. ‘Only lazy violinists play the viola’, he would say;6 and he sometimes betrayed a casual attitude towards the instrument in his choice of violists. Violinists in the Chamber Players were expected to double on the viola, regardless of whether they had any special feeling for it – in the Sixth ‘Brandenburg’ Concerto, Busch used four or even five players for each of the two solo viola da braccio parts. Blanche Honegger, who had never studied the viola but would happily switch from violin to viola and back again during the course of an evening – she did so in all the concerts of the Trio Moyse – was his kind of musician. He would have endorsed her comment: ‘If you can play the violin, you don't have any difficulty playing the viola’.

On 12 August 1909 Adolf and Fritz presented a farewell musical evening at the Beckerath house in Pyrmont. Next morning Fritz was off to the rigours of a Latvian winter and Adolf was thrown into a panic: they had never before suffered a serious parting and he realised for the first time how much their careers would separate them. He still made sure he sent Frieda one of his compositions for her eighteenth birthday that day, a setting in A major of Gottfried Keller's poem Abendlied: there would be a similar present every year up to her 55th birthday, nine days before her death. Since the spring they had forged an understanding that they would marry as soon as Adolf's future was settled; but naturally the Grüters family were worried about an engagement between two teenagers, neither of whom had experienced a relationship with anyone else. Within a week of her birthday, Frieda's father was trying unsuccessfully to talk her out of committing herself to Adolf so early; and brother Otto told her point-blank that the first love of an eighteen-year-old lad was hardly likely to be his last. All such remonstrations were in vain and only a few days later Otto was noting in his diary: ‘Adolf and Frieda much together’. Later that year, the Grüters parents even forbade the pair to communicate directly, which increased Adolf's feeling of isolation. But love soon found a way to circumvent the ban – Frieda's best friend in Bonn, Hanna Zorn, became a willing conduit for letters and messages. There was no doubting Adolf's devotion: Hanna testified that one evening in the winter of 1910–11, when Frieda was staying with the Zorns to prepare for her exams away from the musical uproar of the Grüters home, Adolf stood outside in the deep snow with his violin, serenading his beloved. By then it was tacitly accepted that they would wed as soon as he had embarked on his career.

Through Eldering, Busch had come to know Brahms’ friend Dr Gustav Ophüls, a redoubtable pianist from whom he gleaned much information about the way Brahms liked his works to be played.

This crisis in his life – when he cut himself off from the landscape that had formed him and the tradition that was his main source of cultural nourishment – is perhaps the best point at which to consider Adolf Busch the man, through the perceptions of relations and friends. Like his brother Fritz, he was deceptively tall, a little under six foot (1.79 metres): his heavy build in adulthood made him appear stockier and his skiing accident left him with one leg slightly shorter than the other and an almost imperceptible limp. ‘He had a peasant figure – he wasn't slim and he wasn't fat’, his niece Hildegart Nicholas said. As Evelyn Rothwell saw him, ‘He was like a large, benign bear, slightly shaggy, always with his hair falling over his face – a round, highly coloured face and bright, piercing blue eyes. He was always warm, outgoing, interested, eager – almost like a child’. This view was echoed by Dea Gombrich: ‘It was almost a child's face’. Meeting him with his son-in-law in 1939, a journalist reported that ‘his unlined, pink face and athletic figure make him look almost as young as the slight, boyish Serkin’. In Toni Booth's eyes ‘He was tall, with very broad shoulders, and looked as if he liked running’. And Amalie Serkin saw him as ‘not at all clumsy in appearance but stately, though never pompous – just a tall, big, blond man’. As a boy he had fair hair but it had darkened to reddish-brown by his early twenties – although in his fifties he still struck the young Eugene Istomin as ‘a great blond giant’. In the late 1920s and early 1930s he sported such a short crewcut that on his second visit to America he was described as ‘bristly haired’. Robert Dressler, Busch's pupil in his last years, said: ‘To me he always looked perfectly healthy, hale and hearty. He had very red cheeks, which is typical of a certain type of mostly southern German’. Conte Enrico di San Martino, president of the Accademia di Santa Cecilia, wrote:

Adolf Busch was a towering figure in the musical life of the twentieth century. He was also one of the great individuals of his time, a man of unquenchable idealism, integrity and intellectual rigour who lived out his beliefs and often suffered for them. Now that we can see the twentieth century entire, it is difficult to think of a more important German musician than Busch (except, perhaps, Hindemith) from that era. As man and artist he put most of his contemporaries in the shade and his life was an expression of almost heroic honesty and simplicity.

Yet he is not as well known today as he should be. His career as violinist and composer, like those of so many central Europeans, was disrupted by two catastrophic wars; and his decision to boycott his native country in 1933, when he could easily have stayed and prospered as others did, further fractured his life. This one action made him an exile, cost him the precious cultural nourishment of his native land and deprived him of his most devoted audience, virtually ending his prospects as a composer. Five years later he renounced all his concerts in Italy, where he was hugely popular, in protest at Mussolini's anti-Semitic laws. In America, where he settled at the end of 1939, his kind of musicality – which placed vigour and expression above virtuosity – was not fully appreciated. Any one of these setbacks could have spelt death to such a sensitive artist; and yet he rose above even the mental devastation which went with being a German, in the knowledge of what his people were doing during the Hitler decade.

In one biography of Wilhelm Furtwängler, it is implied that the Busch brothers found it easy to leave Germany in 1933. In another, they are listed as ‘expelled artists’. In a study of Furtwängler's recordings, it is stated that in forsaking their native country they ‘did so not because they were better men than Furtwängler, or had greater foresight, but because they had different priorities’.

While the rest of Europe went to war, life continued relatively normally for the Busches and Serkins in neutral Switzerland, although it seemed far from certain that Hitler would respect that neutrality and refrain from invading. Frieda, chafing at the compromises she felt the Swiss were making with their Nazi neighbours, fired off a letter to Werner Reinhart in which she complained about the engagement of Furtwängler to conduct in Winterthur and the willingness of the Winterthur City Orchestra to continue giving concerts in Konstanz, on the German side of the border – and incidentally chided Reinhart for not supporting the Lucerne Festival. After an interval Reinhart wrote a seven-page rejoinder, setting out the Swiss policy of neutrality in music, as in other things, and questioning the validity of excluding artists such as Walter Gieseking from the Lucerne event on purely political grounds. Much of September was spent by the Busch party at the little village of Eriz near Thun, where the reality of the international situation could be held at bay for a few weeks. Joseph Segal, who stayed with his mother in the same small three-storey house as the Serkins, found that he was expected to have his violin lessons upstairs, while Serkin practised thunderously downstairs. ‘Play forte!’ was the riposte from Busch, who rode up the hill on a bicycle from his own holiday home for the lessons. ‘He would come in, panting very hard – he was quite a heavy man – and take his working violin straight out of its case’, Segal remembered. ‘He would play with me a bit here and there.’

This talented pupil, born in Haifa of Russian parents, came with the recommendation of Sir Adrian Boult, who rehearsed the Beethoven Concerto with Segal and the BBC Symphony Orchestra as part of the first prize that the then fourteen-year-old won in the 1938 British Empire Violin Competition. Busch relented in his opposition to teaching prodigies because he was so taken with Segal's father Levi – who was still based in Palestine most of the time, while Joseph was accompanied abroad by his equally pleasant mother, Yaffa.

Sociologist and dance practitioner Christophe Apprill provides a solid historical overview of tango dance. He then explores gender relations and roles in tango by examining tango stereotypes in relation to tango dance, while opening new perspectives on contemporary dimensions of globalized tango scenes.

Link and Wendland introduce the Cambridge Companion to Music by describing the art form’s multicultural orgins and its stereotypical associations; summarize the state of tango research to date; and provide brief overviews of the twenty book chapters.

Wendland and Link discuss post–Golden Age tango by comparing the life and works of its two great pillars: Horacio Salgán (1916–2016) and Astor Piazzolla (1921–1992). They offer insight into how these tangueros traveled on two distinct paths both in the trajectory of their careers and the development of their styles, and how they shaped the next generation into the twenty-first century.

Scholar and guitarist Eric Johns traces the historical and stylistic lineage contemporary of tango guitar performance practice. He highlights two important schools of playing established by Aníbal Arias (1922–2010) and Roberto Grela (1913–1992).

Ignacio Varchausky examines tango music through its standard instrumental performance practices. He draws on the orchestral styles of two Golden Age orchestras, those of Juan D’Arienzo (1934–1975) and Aníbal Troilo (1937–1975), and illustrates with important archival recordings and scores from the tango repertory. He explains musical techniques and practices that may provide a listener with sounds of tango’s history, and how musically embodying the art form may advance one’s understanding of its culture.

Romina Dezillio considers female tango singers’ artistic and social contributions to the professionalization of women within the national and international tango scene. Her study of the consolidation process of the tango cancionista (female tango singer) during the 1930s in Argentina reveals gender-based relationships between the tango canción and Argentine society as she highlights the personal styles and careers of three star cancionistas: Rosita Quiroga (1896–1984), Azucena Maizani (1902–1970), and Libertad Lamarque (1908–2000).