I woke up this morning with the start of Schubert’s Piano Sonata in A minor D 537 going round in my head. This start powerfully and rhythmically with large A minor chords – only the occasional black note, G sharp, appears. But in my head I felt my hands shaped over the key a semitone below, G sharp minor. The gestalt is built on black notes with white ones between. g sharp minor has 5 sharps in its key signature: A minor has none. My brain had done this so that the sound of the Schubert in my head was the true A minor.