Bartok's Concerto for Orchestra has been regarded as one of the seminal works of the twentieth century.
But without the friendship between its composer and the conductor Fritz Reiner, the work might never have been created.
Bartok had been one of Reiner's mentors when the aspiring conductor was studying in Hungary.
Now, with his teacher and friend in the US, ill and in need of money, it was Reiner who helped return the favour and secure the Concerto's commission.
Professor David Cooper tells the story of the relationship between Bartok and Reiner and considers the importance of their connection.