When were flats invented?

Answer 1

That is an interesting question, the first keyboard instruments were hydraulis - which was a water organ that had the seven modern natural notes that we know today but soon composers discovered that in between the first and second, second and third, fourth and fifth, fifth and sixth and sixth and seventh degrees of the scale - extra notes 'foreign' to the scale could be added and those notes are now represented by the modern-day black accidental keys - when starting major scales on different notes (such as G major or F major). Each black key can have two names based on what the bordering white keys are in modern tuning. For example the black key between F and G can be called 'F-sharp' which means that it is an F note which has been raised by a semitone - and at the same time it can be called 'G-flat' which means it is a G note which has been lowered by a semitone. The name of a black key (flat or sharp) is dictated by the major scale and which letter names have already been used - for example a F major scale would go like this F, G, A, Bb, C, D, E, F (not F, G, A, A♯, C, D, E, F). Flats and sharps - the accidentals - probably didn't exist until about the Baroque era, when harpsichords we're invented and I'd say the natural keys are older.