Her death was announced by the Hildebrand Project, which did not give a cause.

Alice von Hildebrand Courtesy of the Hildebrand Project

Von Hildebrand was a co-founder of the organization, which is based at Franciscan University of Steubenville in Ohio, and promotes the work of her husband, Dietrich von Hildebrand, who fled Hitler’s Germany, founded an anti-Nazi newspaper and championed Catholic personalism, a movement that emphasizes the importance of each individual. He died in 1977.

Like Dietrich, von Hildebrand fled the advancing German forces during World War II, traveling from Belgium to New York City, where she studied under her future husband as an undergraduate and graduate student. She later worked as his secretary and collaborator, typing his manuscripts, translating his essays into English (her first language was French) and co-writing books such as “The Art of Living” (1965), which began by extolling the value of reverence as the cornerstone of a moral life.

Von Hildebrand spent decades championing the legacy of her husband, whom Pope Pius XII reputedly called “the twentieth-century Doctor of the Church.” But she also became a noted Catholic philosopher in her own right, teaching at Hunter College in Manhattan for 37 years, writing essays for the Catholic News Agency and making dozens of guest appearances on Eternal Word Television Network, the Catholic media empire known as EWTN, where she was often interviewed by Mother Angelica, the network’s founder.

“While soft-spoken and meek in physical stature, Alice was nevertheless a giant among Catholic women in the 20th century,” wrote Michael Warsaw, the head of EWTN and publisher of the National Catholic Register, in a tribute after her death. Von Hildebrand, he said, “defended truth, beauty, goodness and authentic womanhood in an increasingly hostile secular and relativistic age.”

As von Hildebrand saw it, the modern world was in a state of “total confusion,” with the forces of secularism pitted against the Catholic Church. She opposed gay rights and abortion – at a 1995 conference in Montreal, she suggested that people demonstrating for abortion rights were possessed by the devil – and considered the French philosopher and feminist activist Simone de Beauvoir her “philosophical archenemy,” arguing that the feminist movement had destroyed the institutions of marriage and the family.

“I would not call myself a Christian feminist but a champion of femininity,” she told the Jesuit magazine America in 2014. “The sublime beauty of the female mission as virgin, wife or mother has been so degraded that I felt a calling to shed light on ‘the privilege of being a woman,’ ” the title of one of her most popular books, published in 2002. In that book and others, she argued for the sacredness of women’s bodies and said that women had a key role to play in advancing the world, notably as mothers and wives.

The Catholic philosopher Alice von Hildebrand with her husband, fellow philosopher Dietrich von Hildebrand, in Salzburg, Austria, in the late 1960s. Courtesy of the Hildebrand Project

“I think that a man should thank God for being a man because he’s given a very clear mission to protect. A woman should thank God for being a woman because her very special mission is to give life, to corroborate with God,” she said in a 2018 interview that Crisis Magazine published after her death. “I love it! And the older I am, the more I love being a woman. Which doesn’t mean to denigrate what manhood is, but simply to say that this is what He wanted me to do.”

Von Hildebrand faced misogyny at the start of her teaching career, when Catholic colleges in the New York area told her they would not hire a female philosophy instructor. She later encountered anti-Catholic sentiment at Hunter College, which she described as “a city university in a fortress of secularism.” She continued to use her maiden name after marrying Dietrich von Hildebrand, because his work was not widely admired at the school, and said she did not receive tenure for 14 years because of hostility from colleagues.

But by all accounts, she had a profound impact on her students, some of whom converted to Catholicism as a result of her philosophy courses. She never proselytized in the classroom, she said, but sought to shake the foundations of relativism and encourage students on their search for objective truth, a journey that for her led directly to God.

“The great tragedy of today is that truth has been replaced by preferences, goodness by whim and beauty by ‘fun,’ ” she told the National Catholic Register in 2014. “In my 37 years of teaching, the overwhelming majority of students I encountered were of the belief that truth, goodness and beauty were relative: They were whatever you wanted to make of them. … The reality is far different. We are in a severe moral crisis in which the eternal truths have been exchanged for temporary fads.”

The third of five children, she was born Alice Marie Jourdain in Brussels on March 11, 1923. Known to friends and family as Lily, she was taken to church from a young age by her father, a daily communicant. When the Nazis invaded Belgium in May 1940, she and an older sister were sent to live with relatives at the Waldorf Astoria hotel in Manhattan.

In her 2014 book “Memoirs of a Happy Failure,” she recalled that she and her sister were sailing to New York on a passenger ship when it was intercepted by a German U-boat, which announced that it would give passengers an hour to board lifeboats before torpedoing the ship. The U-boat ultimately left them alone, sailing off into the Atlantic, but for a moment von Hildebrand was faced with the prospect of her own death, as she realized there was no room on the lifeboat.

“With a clarity and precision that approached the supernatural, all of a sudden, in a single flash, I relived everything I had ever done, failed to do, thought, imagined, and felt,” she wrote in the memoir. “The experience was overwhelming, and convinced me of God’s goodness. Could I not assume that, at the very moment of death, God would grant this experience to everyone, so that each person would have the chance to say, ‘Have mercy on me, my Lord’?”

Von Hildebrand studied at Manhattanville College of the Sacred Heart in New York, where one of her philosophy professors invited her to attend a talk by Dietrich von Hildebrand, who was 34 years her senior. She started taking classes with him at Fordham University in the Bronx, where he was a philosophy professor, and after she earned a bachelor’s degree in 1944 she formally enrolled at Fordham, receiving a master’s degree in 1946 and a doctorate in 1949.

She and Dietrich married in 1959, two years after the death of his first wife, Margarete. By then, von Hildebrand had started teaching at Hunter College, now part of the City University of New York. She later taught at institutions including the Franciscan University of Steubenville, where she was on the board of trustees for more than a decade, and the Notre Dame Institute in Arlington, Va., which was acquired by Christendom College in Front Royal, Va.

Survivors include a sister.

At her 90th birthday gala, von Hildebrand was formally named a Dame Grand Cross of the Equestrian Order of St. Gregory, an honor conferred by Pope Francis. Accepting the award, she credited her husband with teaching her the value of philosophy.

“His approach showed that philosophy is not an abstract discipline. It is life,” she said. “It involves my heart, my intelligence and my will, and therefore opens a vista of greatness and beauty that most of us are not aware of. … He showed me that what we call Christian philosophy is not an abstraction, it is simply reason baptized by faith.”