Born on the 23 December 1831 at Gandelain in the Orne region, Marie-Azélie Guérin was an intelligent and industrious young woman.
She had given consideration to entering religious life but the Superior of the Hôtel-Dieu of Alençon bluntly discouraged her.
Disappointed, she decided to learn the trade of lace-maker. She rapidly excelled in this trade and at the age of 22 years she was running her own business at Rue Saint Blaise in partnership with her older sister, Marie-Louise.
Soon afterwards, however, Marie-Louise left the business to enter the Visitation Convent at Le Mans. As Sr. Marie Dosithée, she remained a constant spiritual advisor to Zélie, as well as to their young brother Isidore, the youngest child of the family.
Zélie was as proficient with the pen as with the needle. In a most lively manner, she recounted to her sister at the Visitation Convent – as well as to her eldest daughters boarding at Le Mans close to their aunt – the minute details of her daily life. It is largely thanks to this correspondence that we have some of the more delightful details from the childhood of Thérèse.