Last week, I visited a friend — a Benedictine sister — at her monastery near St. Cloud. Some years ago, when we worked together on social-justice issues, I savored her energy, lively sense of humor and commitment to hard, incremental work. I admired, too, her private critiques of priests who sought to rule their parishes and female colleagues with princely sovereignty.

Like me, she grew up Catholic during a tumultuous time, when many institutional doors were opened to change and subsequently closed halfway or slammed shut altogether. Unlike me, she committed her life to the service of that church.

My friend was in Rome last week, and I thought of her when I heard the disappointing, though expected, news: Pope Francis, richly compassionate and refreshingly open-minded on so many issues in society, told a Swedish reporter that the Catholic Church will likely never ordain women as priests. His reason: 2,000 years ago in a traditional Jewish culture, Christ chose only men as apostles. Twenty years ago, Pope John Paul II reaffirmed that exclusion.

Aside from my general disappointment — haven't the past 50 years demonstrated in field after field women's capacity, gifts and calling to lead? — I feel a particular discontent on behalf of my friend and the other women who live as religious sisters in the U.S.

Over the past half-century, between 1965 and 2015, the number of American nuns fell from 180,000 to fewer than 49,000. The number of priests fell as well, but far less precipitously: from 59,000 to 38,000.

Religious sisters are a dying breed, without the new recruits essential for survival. According to researchers at Georgetown University, 91 percent of religious sisters in the U.S. in 2009 were 60 or older. Only 1 percent were younger than 40.

Much of this is due to vast number of opportunities that are open to women. Equally important: The daunting challenge in today's ferociously secular world of vowing to live under the constraints of poverty, chastity and obedience.

But some of young women's lack of interest in religious life is surely due to the stubborn constraints on how women are allowed to serve in the Catholic Church. Countless women, from Jesus' mother Mary to Mother Teresa, are venerated by Catholics. But only men are allowed to administer sacraments as Christ's representatives on earth.

For 12 years, through elementary school and high school, I was taught by nuns. Their exoticism fascinated me. I admired their intelligence, craved their approval, feared their ferocity.

The days of sisters providing cheap, abundant labor in Catholic schools and hospitals are long past. At convents and monasteries these days, nursing homes are growing. Leaders plan for the day the last sister turns off the lights for the last time.

Last week, as I joined my friend and a few dozen grey-haired sisters for noonday prayers and a simple meal, I recognized how much these women still have to teach me. How to live in hope in the face of aging and disappointment. How to live in community, with prayer, hospitality and work at the center. How to share old talents in new ways. How to listen for what else God has planned for us. How to plan for our own extinction.

I was struck by the girlishness of the women's voices as they sang, without the strain or cracks that often come with age. My friend had a simple explanation: The sisters gather for prayer four times a day. There is always singing.

Lynda McDonnell is a writer in Minneapolis. Her blog can be found at www.lyndamcdonnell.com.