How did Marin Mersenne contribute to the history of equal temperament?

The French philosopher and mathematician Marin Mersenne contributed to the history of equal temperament by writing about the system in 1636.1

While earlier figures such as Vincenzo Galilei (1581) and the Chinese musicologist Zhu Zaiyu (1596) had previously proposed or described systems of equal intervals, Mersenne’s work helped document the theoretical development of this tuning method. Equal temperament eventually became the standard for Western music because it divides the octave into 12 equal semitones, allowing instruments with fixed intonation to play in all keys by distributing small intonational defects equally across the chromatic scale.12