Every instrument has one, some many: a person whose expression is revelatory, whose technique is both effortless and boundless and whose audience never wants to stop applauding. These extraordinary musicians may still be alive, selling out concerts and racking up views on YouTube and likes on social media. Others have been gone for decades, even centuries, their historical distance only adding to their mythic reputation. Andrés Segovia or Joe Satriani on the guitar, Luigi Boccherini or Yo-Yo Ma on the violoncello, Niccolò Paganini or Hilary Hahn on the violin – such musicians have shaped the identity of their instrument by dint of unparalleled technical and artistic mastery.