In the second part of the little story of musical notation, we have seen appear neumes and have discovered that musical notation at this time corresponded more to an aide-mémoire than to a vector of propagation. In the XIth century, a new fact has considerably enrich musical writing: in order to make their work easier, some scribes used to first draw a light line on their support: it was the beginnings of the staff.

Little by little, the use of this line increased, then became ink-drawn and marked with a letter corresponding to the note assigned to this line. This letter is thus the ancester of our modern keys. A bit later, a second line was added, representing the quint, then a third one, in the middle of the two first. People thus realized that each note had its own place on the “staff”. During the XIIth century, the use of a fourth line was spread, later, in the XIIIth century, a fifth one was added.

The use of the “key” fixed all intervals between notes once and for all. Yet, remained the problem of B, which was mobile and was either a half-tone lower than C or a half-tone higher than A. It had thus to be differentiated: B forming a half-tone with C was represented by a square and the other B, by a circle. This was specified, either just after the key (our actual key signature), or in the text (the origin of accidentals).

From the XIIIth century, people started using natural signs (then confused with sharps) and flats for other notes than B: F and C-sharp, and in the XIVth century, G and rarely D-sharp (does not this order remind you something?). At the beginning of the XVIth century E-flat appeared. At the end of this same century was invented chromatism, the flat-natural-sharp system has thus become without limit. It can be said that in the XVIIth century, the classical notation was fixed and won’t be subjected to many changes.

At this stage, musical writing perfectly informs on note pitches and can become a real vector of music propagation. Rhythmic notation evolves the same way, but I will come to this in a next post.