After a year with her parents, Guyart was invited to move in with her sister and brother-in-law, Paul Buisson, who owned a successful transportation business.

This place was elevated, and below it lay a majestic and vast country, full of mountains, of valleys, of thick mists which permeated everything except the church ...

[5] In 1631, after working with a spiritual director for many years, Guyart decided to enter the Ursuline monastery in Tours to answer her religious vocation.

After having professed her vows in 1633,[6] she changed her name to Marie de L'Incarnation;[7] that Christmas, she recounted a powerful vision, which functioned as the catalyst for her mission to New France.

On the roof of a small church in this distant, foggy landscape sat the Virgin Mary and Jesus; she interpreted this as the mother and son discussing her religious calling to the new land.

She recounted the vision to her priest at the Order, who informed her that the nation she described was Canada, and suggested that she read The Jesuit Relations;[8] from this Guyart concluded that her vocation was to help establish the Catholic faith in the New World.

Over this time, she maintained a continuous correspondence with Jesuits in Quebec who were supportive of a female religious presence, which might facilitate the Christianization of Huron women; Guyart's Mother Superior in Tours, and her pre-Ursuline religious director Raymond de Saint Bernard were largely unsupportive, the latter suggesting that it was too lofty for a lowly laywoman.

Her brother, Claude Guyart attempted to persuade her into abandoning her mission by accusing her of parental neglect, and by revoking an inheritance designated for her son; these measures did not deter her.

[10] Guyart's initial financial concerns for the funding of the journey, and the establishment of a convent in New France were resolved when she was introduced to Madeleine de la Peltrie on 19 February 1639.

De la Peltrie's new marital status gave her the legal authority to sign over the bulk of her estate to the Ursuline Order, thereby fully funding the mission.

[11] Following this, the Ursuline went to Paris, and signed legal contracts with the Company of One Hundred Associates, and the Jesuit Fathers, who were responsible for the colony's political and spiritual life, respectively.

They were accompanied by a fellow aristocratic Ursuline Marie de Sanonières, the young commoner Charlotte Barré, three nurses, and two Jesuit Fathers.

[citation needed] Guyart's early interactions with Native populations were largely shaped by the constraints created by differing lifestyles, illnesses, and alliances.

Indigenous divisions of manual and domestic labour by gender and age diverged significantly from European conceptions of masculine and feminine spheres of work.

Smallpox outbreaks from the 1630s to the 1650s ravaged Native populations, leading them to believe that Jesuits and Ursulines were imparting disease through their religious practices and paraphernalia.

Fears that baptisms, holy icons, and crosses were the source of all epidemics greatly limited the groups' interactions, and strained Marie's relationship with Natives in her first decades in New France.

[15] The most volatile relationship Guyart and the Ursulines faced revolved around the conflict that pitted the French, Huron, and other indigenous allies against the Iroquois.

Her perceptions of similarities between European Christians, and the potential converts in the New World were the upshots of a cloistered convent life, and largely non-existent experiences with other cultures;[19] such seclusion allowed for an over-simplification of her ambition to spread God's word transnationally.

[20] According to Natalie Zemon Davis, the integrative approach towards Native interactions that developed from this mindset was dissimilar to the Jesuit's methods of establishing relationships in New France.

Jesuits adopted Native roles in the presence of First Nations peoples, but were quick to shed these association when outside the confines of their settlements;[21] this double life made any fully integrative experience, or universal mindset impossible.

In the necrology report sent to the Ursulines of France, it was written: "The numerous and specific virtues and excellent qualities which shone through this dear deceased, make us firmly believe that she enjoys a high status in God's glory.

"[26] In addition to her religious duties, Guyart composed multiple works that reflected her experiences and observations during her time in the New World and the spiritual calling that led her there.

In relation to her work with the indigenous population, Guyart learned the Innu-aimun, Algonquin, Wyandot, and Iroquois languages, writing dictionaries and catechisms in each (none of which are extant), as well as in her native French.

[13] Her collection of works discuss political, commercial, religious, and interpersonal aspects of the colony and are helpful in the reconstruction and understanding of New France in the seventeenth century.

The Pontiff waived the requirement of two miracles for Guyart, and she was granted equipollent canonization alongside François de Laval, the first Bishop of Quebec.

At Laval University, in Québec City, there is the Centre d'Études Marie de l'Incarnation, that is a multi-disciplinary program pertaining to theology and religious practice.

[33][failed verification] Guyart's life story was adapted into a documentary-drama by Jean-Daniel Lafond, entitled Folle de Dieu (Madwoman of God) (2008).