“Be careful,” I said to my aunt, as she stood admiring the grapevines in front of our house. “There’s a car coming.”

My aunt is 85 years old and knows enough to watch out for approaching cars. But when the warning came automatically out of my mouth, my cousin Julie knew exactly what was going on.

“It’s the mother thing,” she said.

She was right, of course. And there’s no getting around it, for God evidently placed a nurturing essence in women’s hearts when He told Adam and Eve, “Be fruitful and multiply.”

Still, many women never do multiply, at least not in the classic sense. I can point to countless ladies who are bright and kind and yet still live alone without husband and children.

There are also women like me, who met a nice man and got married, but for one reason or another, never had a family.

Still, it seems that women have that “mother thing” nestled in our hearts, whether we have physical children or not.

And some women may become spiritual mothers.

As a young nun, St. Therese of Lisieux heard about a fierce criminal, who was destined for the guillotine, but who refused to repent. She prayed intensely for the man’s change of heart and then had evidence that her prayers had been answered:

At the execution site, reporters noted that the man kissed the crucifix three times, right before his execution. And what was Therese’s response to this amazing news?

“My first child,” she called him.

Some women follow in St. Therese’s footsteps by nurturing the community around them.

You see these stalwart souls at local churches, singing in choirs or visiting the sick and homebound, and creating a spiritual family. They also are the ones who run church nurseries and pitch in on Sunday school classes.

Many women pour out their loving energies on other people’s children. Think about all the big-hearted teachers, librarians and nurses you have known, who have a special way with little ones. And whose humble prayers at night may be the mysterious spark that changes a child’s life.

“Spiritual maternity is the work of redemption … engendering souls for the kingdom,” writes Joanne Mosely in “Edith Stein.”

Stein, who is now known as St. Teresa Benedicta of the Cross, was a stunning example of spiritual motherhood. A Jewish convert to Catholicism, she entered the cloistered convent but was arrested and sent to the Nazi death camps in 1942.

She ministered tenderly to the women and children imprisoned in the camps and brought a measure of comfort to hearts that were shattered by fear and desperation.

This saint’s unselfish devotion, even in the face of her own death, shows that the deep-seated spiritual essence of mothering is about much more than blood ties. Which is something that any adoptive mother can attest to.

My cousin and her husband had two babies when they decided to adopt a little boy. Their sons rejoiced in their new big brother, and in the simple way of children, showed that love was a matter of the heart, not genetics.

The Blessed Virgin Mary had one biological child, while she was walking upon the Earth. That child, while dying on the cross, entrusted Mary to the care of St. John by saying, “Behold thy mother.”

In that moment, Jesus also gave Mary to each of us, so she became the spiritual mother of the world.

“It is very moving that the Son of God has a human mother and that we are all entrusted to her care,” writes Pope Benedict XVI in “God and the World.”

“The saying of Jesus on the Cross, when he gives Mary to John as his mother, far transcends that moment and reaches right down through history,” he notes.

Mother Mary has nurtured countless spiritual children since that moment, with a myriad more to come. She is a model for all women who are mothers, whether through biology, adoption or spirituality.

Mother’s Day is a wonderful time to rejoice in the way women’s nurturing spirits bring fresh life to the Communion of Saints.

Women share a powerful feature with the Blessed Virgin Mary: We can bring souls to Christ, just as St. Therese did, through our prayers and faithful love, thereby adding more children to the most wondrous family of all. Have a blessed Mother’s Day!