Leopold Mozart was only able to understand his son's musical genius in terms of it being a God-given wonder: "That my boy [...] knows all of this with his 8 years that could be expected of a man of forty years. In short: whoever has not seen or heard it, cannot believe it". In 1764 Wolfgang composed six sonatas in London - possibly after the model of Johann Christian Bach's "Opus 2" - that can either be played as piano trios, as violin sonatas or simply on the piano. "Royal" sources were consulted for the edition: the copy in the British Library bears the handwritten note: "This Volume belongs to the Queen 1788".