The viola is the plangent heart of the string section. A modest instrument, it tends to cede glamour and virtuosity to the showier violin and cello.

But that is deceptive: in a string quartet, the viola holds the music's centre, often moving it through the most complex of harmonies, or expressing its most melancholy moods.

It is no coincidence that the viola is favoured by composers: Mozart, Dvorak, Hindemith, Britten, John Cale, Jocelyn Pook – all viola players.

And when a composer turns to the viola as a solo instrument, particularly in the chamber repertoire, the results can be heart-stopping: sceptics should turn to the third movement of the Brahms Quartet Op 67 and attempt to remain dry-eyed.

News that the 1719 "Macdonald" Stradivari viola could sell for £27m, becoming the world's most expensive instrument, is striking: but the important thing is that it is put into the hands of a wonderful player. We must hear it sing.