Musical Flats and Sharps symbols?

'Accidentals', and other modern music notation seems to have begun in the 9th century, by Aurelian of Réôme, a former monk who who wrote one of the oldest surviving papers on music, the "Musica disciplina". They became more widely used in the 11th century, with the beginning of Western European Classical Music.

That's a good question it think it kind of just happened. I don't think anyone sat down

and said let me think of a symbol for a flat and sharp. It just was done that way and everyone continued