Since the printing press had not yet been invented, if a piece of music was to
be retained , it would have to be copied out by monks, diligently writing
out music for church services. Sometimes the music was written out
in a very ornamented fashion.
Around 1025, Guido d'Arezzo
developed a system of pitch notation using lines and spaces. Until
this time, only two lines had been used. Guido expanded this system
to four lines, and initiated the idea of ledger lines by adding lines above
or below these lines as needed. He used square notes called neumes.
This system eliminated any uncertainty of pitch, which had existed until
this time. Guido also developed a system of clefs, which became the
basis for our clef system: bass clef, treble clef, and so on.
Another important contribution
was his treatise on polyphonic music. This was important as
it led to the development of polyphony by Leonin