When I started having children, I didn’t expect to notice new cracks of brokenness in the world. Sitting beside a fellow mother with her baby on a plane once, I was told of how this young lady was returning from a visit to the father of her child. She’d tried to get him to be a part of their child’s life, with no success. Now she was flying back home to live with her parents.

Another time an older woman looked longingly at my child while I walked around town, and told me, “Ah, my daughter hasn’t given me grandkids, though she and her boyfriend have been together for eight years.”

During a Wendell Berry book discussion, I remember being shocked when one woman, a fertility consultant and doula, shared, “One of the problems I have with modern motherhood is that I never held a baby until I had one of my own.”

I’ve often recalled Alice von Hildebrand’s exhortation since then: every woman is called to be a spiritual mother, regardless of whether she is married or not, whether she has children or not. A mother, she says, “is the very essence of femininity.” Indeed, she goes further: “Spiritual motherhood is more important than biological motherhood. There are plenty of women who are biological mothers and yet are not mothers at all.”

Colleen Carroll Campbell echoes this in her memoir, My Sisters the Saints. In the midst of infertility, Campbell struggled with what it means to be a woman, until she realized that just about every one of her spiritual heroes – including Edith Stein, Teresa of Ávila, Thérèse of Lisieux, Teresa of Calcutta, Saint Faustina – also did not have biological children. She then reads John Paul II’s work with new understanding: He claimed that “a woman can discover and cultivate spiritual maternity regardless of her state in life or her ability to bear children.” Indeed, “Every woman is called to be a mother…but there is more than one way to answer that call.”

And the way is not found in idolization of marriage. Campbell, drawing on Stein, notes, “Only in loving union with God can she find the strength and selflessness she needs to be a true spiritual mother.” Above all, a woman desires union with God, a total immersion and transformation in his love.

Few novels explore how motherhood shapes a woman’s soul: Kristin Lavransdatter is one. Another is Sally Thomas’s debut, Works of Mercy. Both Undset and Thomas weave tales marked by theological vitality and spiritual depth, as well as vivid characters and prose. In Kristin, motherhood flows river-like throughout the three volumes; in Works of Mercy, it flows more like a meandering stream, but no less powerfully.

Perhaps surprisingly, Thomas’s main character is a childless widow who loves solitude. “On Mondays I cleaned the rectory for the good of my soul.” With this first line, we are in the world of Kirsty (Kirstaine) Sain, a sixty-something Shetlander transplanted by marriage to the small town of Annesdale in the North Carolina Piedmont. As the story opens, she lives alone in the house left to her by her Baptist husband, Ransome. Kirsty has settled into a quiet life of relative seclusion: she cooks meals, keeps house, goes to confession and Mass, reads Robert Southwell, and, of course, cleans the rectory: “Had I been born in the right century, I might have made an adequate anchoress.”

Cleaning the rectory provides Kirsty with a way of serving others while still maintaining the rhythms of a recluse. After all, she confesses, she has “never been fond of children.” She also doesn’t enjoy, “as a general rule, the company of women. This ruled out the altar guild.” But the rectory does bring her into close contact with young Father Schuyler, the new parish priest. A fiery sermonizer in the pulpit, Father Schuyler craves solitude perhaps even more than Kirsty: He becomes known for hiding from his parishioners after Mass and bolting his door.

Though Kirsty had not been able to give her husband a child, she has returned to the Catholic faith of her childhood. And despite her designs for a more hermit-like existence, a motley band treads its way into her life, not least of which is the loquacious Janet Malkin – “a conversation in search of something to be about” – and her quiver-full family, including four-year-old Henry. Kirsty also finds herself tending to a blind, blue-skinned cat and a plastic statue of the Infant of Prague. The barren, bereft Kirsty, despite her reluctance, slowly is taken out of herself as she encounters those in need of a mother, including Janet herself.

Works of Mercy possesses the finesse and wit of Thomas’s poetry, and she spins us a tale beautifully wrought, treating the human and the transcendent with grit and grace. It’s also a story of the mystery of salvation through the vocation of motherhood. Edith Stein wrote that, at the deepest part of a woman’s being, there is a “yearning to achieve a loving union which...furthers the desire for perfection in others.” Early on in her life, Kirsty’s chances at achieving such a loving union are thwarted, and there is a part of her that, ever after, holds back from giving herself completely to others. Her grief for those she’s loved and lost is “complicated by regret, chiefly the regret that you were not sadder than you were.” And if one is not grieving enough, she muses, “because you had not loved very adequately what you had lost – what then?”

Spending time with Kirsty Sain is like easing on a pair of well-loved slippers. She may be taciturn and somewhat frigid, but with her wry humor and keen eye, she makes for delightful company. She’s clear-eyed and unsentimental (“It seemed to me that to be different was to be like anybody. There was nothing so very remarkable in that. It was the human condition”), and she tells her story in beautiful prose. She describes her childhood Masses thus: “I gazed at the clear mullioned windows, holding the early light in summertime. Their crosshatched shadows fell over people’s sun-bright faces; their glow turned the plain-washed walls to gold as the priest’s Latin whispers fell on the air.”

Too often we think in terms of discrete life stages: Once we get married, perhaps, then we can start thinking about being a mother, when really, to be a woman is to be called to motherhood.

Like Robert Southwell’s poem “The Burning Babe,” whose lines also prove prophetic for Kirsty’s story, the novel concludes during the Christmas season, when Kirsty holds someone else’s baby in her arms.

But then, what does it matter that the child is not her own? “To be a mother,” wrote Edith Stein, “is to nourish and protect true humanity” and to be especially receptive “for God’s work in the soul.” Through Kirsty’s (sometimes grudging) works of mercy, she becomes more and more open to the Mercy that is always working on and through her.

Through the Mercy Himself, the childless cleaning lady Miss Kirsty and the unsociable Father Schuyler will become truly a mother, and truly a father. Slowly, haltingly, Kirsty confronts the shadows of regret, grief, loneliness, and loss, and swims in the mystery of salvation.

Today’s crisis of fatherhood is also a crisis of motherhood. Perhaps most achingly for me, I see both the need for mothers of young mothers, and I see older women who are effectively childless, because they are either estranged from their own children, or they’ve no young men and women to whom they are ministering in their lives. Too often we think in terms of discrete life stages: Once we get married, perhaps, then we can start thinking about being a mother (or father), when really, to be a man is to be called to fatherhood, and to be a woman is to be called to motherhood. It is not a matter of having one’s own biological children, but rather of fulfilling what Edith Stein calls motherliness: the key characteristic, and vocation, of all women, single or married:

Only, the motherliness must be that which does not remain within the narrow circle of blood relations or of personal friends; but in accordance with the model of the Mother of Mercy, it must have its root in universal divine love for all who are there, belabored and burdened.

“One who is mother only to her own children is not a mother,” says George MacDonald’s narrator in his novel Sir Gibbie; “she is only a woman who has borne children. But here was one of God’s mothers.” Kirsty herself, despite her own wounds, becomes one of God’s mothers, discovering that it is never too late to respond to the call of Mercy.