ROME – Though the Vatican has been a bit preoccupied touting the fifth anniversary of Pope Francis’s eco-encyclical Laudato Si’ – funnily enough, the current pope, the one who can make or break careers today, always seems to get more official love than his predecessors – last Saturday also marked the 130th anniversary of another landmark papal document, one that arguably made Laudato Si possible: Leo XIII’s 1891 encyclical Rerum novarum.

A response to the rise of industrialized capitalism, Rerum novarum, subtitled “Rights and Duties of Capital and Labor,” launched the modern tradition of Catholic social teaching.

A gifted intellectual who amused himself by anonymously composing riddles in Latin verse for a Roman newspaper, Pope Leo looked around and saw soulless robber baron capitalism on one side and socialism and communism on the other, setting the stage for an impending social apocalypse. Rerum novarum was his effort to offer a Christian alternative, one premised on both a right to private property but also the duty of the state to intervene in economic life to promote justice and to defend the poor, supporting trade unions and collective bargaining.

It’s the foundation for every other bit of social analysis offered by a pope over the last century and a half; three subsequent encyclicals, Quadragesimo anno by Pius XII, Mater et magistra by John XXIII, and Centesimus annus by John Paul II, were published on its anniversary.

Among other things, Leo XIII was the first pope to articulate what would later become known in Catholic social teaching as the “preferential option” for the poor: “The richer class have many ways of shielding themselves, and stand less in need of help from the state; whereas the mass of the poor have no resources of their own to fall back upon, and must chiefly depend upon the assistance of the state. And it is for this reason that wage-earners, since they mostly belong in the mass of the needy, should be specially cared for and protected by the government.”

In terms of the composition of the encyclical, the base draft was written by the pope’s good friend Cardinal Tommaso Zigliara, a Dominican who had been ordained to the priesthood in Perugia in 1856 by then-Archbishop Vincenzo Gioacchino Raffaele Luigi Pecci, the future Pope Leo XIII.

Born on the island of Corsica, like Napoleon, Zigliara entered the Dominicans at the age of 18 and quickly distinguished himself for his intellectual chops. He went to become a professor and eventually rector at the Dominican-run University of St. Thomas Aquinas in Rome, better known as the “Angelicum,” where he became the day’s leading exponent of Thomistic realism as an alternative both to right-wing traditionalism and left-wing modernism.

When Leo became pope in 1878, he made Zigliara a cardinal in his first consistory and eventually named him to a robust seven dicasteries in the Vatican, including serving as prefect of the Congregation for Studies. Behind the scenes, he was a key advisor to Pope Leo, who trusted his friend’s balanced and insightful way of sizing things up.

Zigliara was also the primary drafter of another of Leo’s encyclicals, 1879’s Aeterni Patris, which advocated a revival of Christian philosophy based on the thought of Thomas Aquinas, not in the sense of a simplistic return to the past but a recovery of the spirit of reasoned investigation that guided Thomas himself. Leo was worried that philosophy was splintering into secular thought detached from faith and a fussy traditionalism that knew only how to condemn, and he saw in Zigliara the heir to an intellectual tradition that offers a third, and better, choice.

To be sure, Zigliara wasn’t the only influence on Rerum novarum. Historians say Pope Leo also drew on the ideas of German Bishop Wilhelm Emmanuel von Ketteler; English Cardinal Henry Manning; Italian Bishop Geremia Bonomelli; Marquis René de La Tour du Pin Chambly, a leading exponent of French Catholic social thinking; and two Italian Jesuits, theologian Carlo Maria Curci and Matteo Liberatore, the founder of Civilità Cattolica.

Yet in assessing those voices, it was often Zigliara upon whom Leo relied.

Today, Zigliara is all but forgotten. There’s an obscure side street in Rome named for him, located north of the Vatican Museums near the Gemelli hospital, the biggest attractions on which are a tattoo parlor and an American barber shop … hardly a fitting legacy for someone who helped transform Catholic thought and laid the basis for its creative engagement with the modern world.

(City planners didn’t even have the good taste to make sure that Via Tommaso Zigliara intersects with Via Leone XIII, named for the pope Zigliara served.)

In that sense, Zigliara is illustrative of a personality type in the life of the Church.

Had he pursued his own career, Zigliara probably would have written his “big book,” the one that made him famous and is still read today. Academies would be named for him, essay collections would be published on the anniversaries of his birth and death, and eager young students today would be writing graduate theses on the key themes of his work. He could be the Corsican Jacques Maritain, for instance, or Yves Congar, or any number of other superstar Catholic intellectuals.

Instead, at the peak of his intellectual prowess, Zigliara put his own work largely on hold while he took on bureaucratic assignments and served as a ghostwriter for someone else, all because the Church, in the person of the pope, asked.

Every papacy is, in that sense, a collective enterprise. It’s the pontiff who gets the credit or the blame, but often their finest moments depend heavily on the labor of others who fade into the woodwork when the moment passes. Yet without those anonymous actors, the greatest turning points in Catholic history never would have happened.

Perhaps what the Church needs is something akin to All Saints Day, celebrating all those saints whose names we don’t know or have been lost over time – “Anonymous Actors Day,” or something like that, recalling all those past figures who sacrificed their own personal interests in order to serve the whole.

In the meantime, as the Vatican celebrates Laudato Si this week, it might want to spare a moment to thank Tommaso Zigliara – because without him, it’s unlikely there would be an eco-encyclical to celebrate.

Follow John Allen on Twitter at @JohnLAllenJr.