In the days since his death, Pope Francis has been called a reformer, outsider, influencer and modernizer. He was all of these things. But he was also the steward of the oldest institution in the Western world. He protected the Roman Catholic Church’s doctrine — even if he did so in his own style.

That is evident in one of Francis’ last writings, which was provided to The New York Times and has not previously been published. It’s a short foreword to a book, written for young Catholics, about the church’s teachings on love and marriage. The book is from the YOUCAT Foundation (short for youth catechism, or doctrine), an organization approved by the Vatican to publish the church’s teachings in a way that young people can understand. The foundation distributes books in 70 languages around the world.

In the foreword, Francis articulates the church’s position on marriage: that it is a priority, one of sacred importance, and is only between a man and a woman. He breaks no new doctrinal ground. Still, the letter illustrates who Francis was as a pope: a pragmatic and compassionate communicator who skillfully repackaged, without necessarily changing, the church’s doctrine for a modern era. (Read the full text here.)

“It’s a confirmation of a legacy,” Raúl Zegarra, a professor of Catholicism at Harvard, said. “It’s really a classic text by the pope.”

His rhetorical style

In his opening lines, Francis captures much of his approach to the papacy.

“In my homeland of Argentina, there is a dance I love very much, one that I often participated in when I was young: the tango,” Francis, the first Latin American pope, writes. He then compares the tango, in all of its “discipline and dignity,” to marriage.

“I am always touched to see young people who love each other and have the courage to transform their love into something great: ‘I want to love you until death do us part.’ What an extraordinary promise!”