An orphan named Agatha was left at a Venice orphanage in 1712, when Vivaldi was teaching children. Her unearthed music is finding a home in regional Victoria.
When Australian Chamber Choir manager Elizabeth Anderson opened an email in 2022, she gave voice to a young woman who had been silent for three centuries.
The singer and harpsichordist tracked down a piece of music written by a Venetian woman named Agatha in the 1700s, when Antonio Vivaldi was composing and teaching.
Ms Anderson formed an immediate impression of the work when a photograph of the manuscript arrived in her email inbox from a library in Italy.
A librarian found Agatha's Ecce Nunc, in the archives of the orphanage where Vivaldi taught music.
"It's fairly youthful handwriting, it looked as though the parts had been either composed or written out by a very young person,"
Ms Anderson told AAP, "I wasn't necessarily expecting it to be of a very high standard."
She keyed the notes into her computer and the glorious sound sent her rushing to her husband, the choir's founder Douglas Lawrence.
"I said, 'What does this sound like?'
"We stood there in front of our computer and he said, 'it sounds like Vivaldi'."
That moment was likely the first time Agatha's cantata had been heard in centuries.
Agatha was one of many children raised at the Ospedale della Pietà orphanage, sent there in 1712 after she was born without fingers on her left hand.
Vivaldi worked at the orphanage teaching girls music in a program to prepare them for marriage and Italian society.
Ms Anderson was taken with the story of the orphans' music as a school girl and revisited the idea when the chamber choir was preparing a Vivaldi Gloria two years ago.
A librarian in Italy pored through the archives and sent through Agatha's Ecce Nunc, which had parts for a first violin and alto and bass singers.
Using the musical style of the era, which doubles the choral lines with orchestral instruments, Ms Anderson was able to fill in the missing parts.
The choir debuted Agatha in Vivaldi's Venice in Terang, rural Victoria, and is set to perform it in Melbourne and the regions throughout April and May.
It will be the finale of Hamilton Gallery's major exhibition Emerging From Darkness: Faith, Emotion and the Body in the Baroque on April 13.
The exhibition features rare works by artists including Peter Paul Rubens, Artemisia Gentileschi and Bartolomeo Manfredi, some of which have never been seen in Australia.
Agatha's music evokes thoughts of all she overcame to compose, perform and ultimately teach.
"She would have grown up knowing that she had been rejected by her parents and the reason why," Ms Anderson said.
"In that time it was considered inappropriate for girls to be composers so ... it's even possible she wrote music in secret."
Centuries on, her story is being heard in small towns and cities on the other side of the world.
"People in Terang were the first people in the world to hear Agatha's cantata.
"They felt very privileged."