Another find in a secondhand book sale was a volume of Dvorak Humoresques. Who knew there were eight of them for piano? I confess I only really knew the Humoresque made famous by Fritz Kreisler, Jascha Heifetz and others in arrangements for violin and piano. Kreisler’s luscious ‘slides’ from one note to another ring in my ears as I think of his recording.

But the Humoresques were actually written for piano. Dvorak was in the middle of a three-year stint as Director of the Music Conservatory in New York. He looked forward to the summer holidays when he could take the boat back to Europe, travel to his summer house in Bohemia and compose without interruption. In 1894 he took with him the sketches for some pieces which, it seems, he had intended to call ‘New Scottish Pieces’. They emerged eventually as Humoresques, a title suggesting ‘good mood’ or ‘good humour’ rather than something amusing.

The Humoresques are charming, folk-like, songful, with an open character. Yet almost all of them are in ‘difficult’ keys with forests of sharps and flats. No 7, the famous one, is in G flat major (six flats). It’s quite tricky to skip about (‘Scottishly’) on the black keys without slipping off and hitting other keys you didn’t mean to hit.

When I was little, I enjoyed sightreading books of piano music, but I used to flick through the pages, checking for key-signatures bristling with sharps or flats and bypassing those pieces in favour of ones in ‘easier’ keys. It was a long time before it dawned on me that some things are actually easier to play in ‘black-note’ keys. It’s to do with the fact that the black keys on the piano lie a little higher than the white ones. If you are playing mainly on the black keys, the white keys lie ‘below’ and don’t get in your way as you move about. Conversely, if you are playing something complicated on the white keys, your fingers may stumble against black keys as you move about. So although it seems counter-intuitive, ‘black note keys’ do sometimes make the pianist’s task easier.

G flat major is the key of one of Schubert’s loveliest Impromptus (D899). Some old editions transpose it into G major, so that the music is easier to read. Easier to read, yes, but not easier to play. I learned it in G major and was mortified when I discovered Schubert wrote it in G flat. When I re-learned it in G flat, I realised that some of the rippling patterns actually lay better under the hands.

In Dvorak’s case, though, I’m not convinced that his use of ‘difficult’ keys was entirely for the pianist’s sake. His choice of six flats for the lovely Humoresque no 7 seems a little bit forced. This one probably is easier in G major, the key in which violinists like to play it. I’ve heard string players play it in various keys, actually – none of them G flat major!

I’ve often felt that for Dvorak, writing in ‘difficult’ keys had some sort of emotional meaning. It’s as though he felt his great melodic gift would mislead people into thinking that composition was easy for him. He wanted to be thought a serious composer in the classical tradition. His mentor Brahms was fond of writing piano music in ‘difficult’ keys, and it may be that Dvorak somehow associated a phalanx of sharps and flats with serious artistic endeavour.