[2] She had six siblings: Jean, Marie-Marguerite (known as "Mariette"), Joseph, Blaise (who died aged 12), Seraphine (the last-born),[3] and Claude.

Her parents were farmers and devout Christians; Bays herself demonstrated great intelligence as a student while studying at school in Chavannes-les-Forts, and demonstrated a particular, though noted, inclination towards reflection and contemplation, while deciding to cease interacting with her peers at school in favor of the solitude of talking to God.

Bays created a small altar in her room at home, where she placed flowers and a statue of the Blessed Virgin Mary.

It was during her adolescence that some peasant farmers could no longer find work due to the introduction of mechanization in agriculture.

But these troubles did not hinder her efforts to serve the poor for she carried milk and bread to them while she would also wash and mend their clothes or even give them new ones to use.

[1] Her devotedness to service of the poor led her to discover the Secular Franciscan Order which she became a member.

But she tried to hide this and did not even take medicine for it until the condition was discovered and she was prompted to see a doctor who made the diagnosis and ruled out an operation.

[2] In addition she began to fall into ecstatic raptures when she would feel the pain of Christ once a week marking his death.

Marguerite grew frail and thin and her brother Jean said she felt like a bag of bones when he had to lift her.

[3] At the time her true condition was unknown and it is said she remained silent in relation to her level of pain during this period.

Pope John Paul II declared that she had lived a life of heroic virtue and proclaimed her Venerable on 10 July 1990.

She was canonized alongside Mariam Thresia Chiramel, John Henry Newman, Irmã Dulce Pontes and Giuditta Vannini at St Peter's Basilica on 13 October 2019.