What musician was the first to use staff lines to notate music

Guido d'Arezzo

Explanation:

The first use of staff lines to notate music can be traced back to Medieval music theorist Guido d'Arezzo. Guido is considered to have invented modern musical notation, as well as the Guidonian hand, a mnemonic device where note names are maped on a hand. He is also remembered for his popular text, the Micrologus.

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