VATICAN CITY, OCT. 18, 2009 ( St. Giovanni Leonardi made the light of Christ shine in difficult times, Benedict XVI said in a message read today at a Mass to mark the 400th anniversary of the founder's death.

The Mass today in St. Peter's Basilica was celebrated by Cardinal Ivan Dias, prefect of the Congregation for the Evangelization of Peoples.

St. Giovanni Leonardi founded the Clerks Regular of the Mother of God. He is also the patron of pharmacists. The Pope reflected on his teaching and role during the general audience two weeks ago.

The papal message was addressed to Father Francesco Petrillo, rector general of the order.

“St. Giovanni Leonardi shines in the firmament of the saints like a beacon of generous fidelity to Christ,” the Pontiff wrote, according to a Vatican Radio report.

The message noted that in a society that was “convulsed” like that at the turn of the 17th century, the saint “struggled so that the light of Christ would shine again among his contemporaries and they would feel the warmth of God’s merciful love.”

Cardinal Dias repeated this point in his homily, saying that Leonardi, “with his luminous life, brought God back to men.”

“His whole life,” the prelate said, “has the seal of the uncontainable and untiring love for the glory of Christ. His missionary zeal was not merely geographic […] but had to be capable of transforming every gesture, every effort, every bit of time and energy into something missionary, and for one single and supreme interest: Christ and Christ crucified.”

St. Giovanni Leonardi, the cardinal said as the Church marks today's World Mission Sunday, wanted an entirely missionary Church, “without the interference of political or administrative patronage,” but intimately directed toward man.

At the close of his customary Sunday recitation of the Angelus, the Pope greeted the Clerks Regular of the Mother of God, who had come for the celebrations of the 400th anniversary of St. Giovanni Leonardi’s death, along with the students of the Colleges of the Propaganda Fidei and representatives of pharmacists, who have the saint as their patron, calling on them “to follow him on the path of holiness and to imitate his missionary zeal.”