Blessed P. Manna, “whose name deserves to be written in gold letters in the annals of the Church” (PAUL VI, Apostolic Letter Graves et Increscentes, 1966), was the founder of the Missionary Union of the Clergy. He was convinced that until priests and bishops were converted to the missionary idea, the missions would continue to be entrusted to just a handful of missionaries who were absolutely insufficient for the Church's universal mission. He envisaged an association of the clergy whose sole purpose would be to animate and instill missionary eagerness in pastors and formators of communities. They, the priests, had to be like a host of soldiers in the trenches who could help and support the ones on the front line. Only on this condition can all the communities become missionary. This Union was planned as a “school of educators to apostolic service lived in universal terms”.
In 1916 the Union was approved by Pope Benedict XV. In a few years the Society spread throughout the world. The First International Congress of the Union (January 3, 1922) stated the need to teach Missiology in the seminaries, a still unknown science in the Catholic formation institutes. In his writings, Father Manna insisted on the irreplaceable role of priests in the proclamation of the Gospel and the education of missionary awareness in the laity. The Union spread rapidly after the Pope recommended its presence in all the dioceses in his Encyclical Maximum Illud (1919).
Through great preaching and publishing activity, Father Manna got ecclesiastics and laypersons involved in the missionary ideal while he challenged young people to carry it out. For him there was no missionary vocation distinct from the priestly or Christian vocation: his Motto was “All Missionaries!”; all baptized persons, but especially “every priest by nature, by definition, is a missionary”, and “the Church's first and fundamental function is the evangelization of the world, the whole world”. This universal missionary spirit must be integrated into the spirit of unity with those that he was the first to call our “Separated Brethren”, “an essential condition for the integral triumph of the Gospel in the world”. Like priests, also men and women religious, together with consecrated lay persons, are the natural workers of the Mission, and with the Decree Huic Sacro (1944), the Congregation of Propaganda Fide offered them membership in the Union too.
With the Decree of October 28, 1956, Pius XII gave the Union the title of “Pontifical” and later renamed it the “Pontifical Missionary Union of the Clergy, Men and Women Religious and the Consecrated Laity”.
At an advanced age, as in a dream, Father Manna drew up his great missionary plan with a prophetic character and a universal scope. He invited the Churches to found Missionary Seminaries to take part directly in the evangelization of the world and to help the young mission Churches.
Father Paolo Manna died on September 15, 1952 and on November 4, 2001 he was declared Blessed by John Paul II.