13 The Dominicans have, therefore, an almost boundless field in which to labor for the common welfare. Wherefore to all of them We wish that in these centenary celebrations they renew their devotion to the holy example of their founder, and make themselves daily more worthy of such a father. In this let a fitting lead be taken by his children of the First Order, and let them be ever more zealous in preaching the Divine Word, such as may give men a reverence for the successor of St. Peter and a devotion to the Virgin Mother, and may spread and defend the truth. But from the Dominican Tertiaries, too, the Church looks for much, if they study to conform themselves to the spirit of their patriarch, in the instruction of the rude and unskilled in Christian doctrine and morality. In this We hope they will be assiduous, as it is a matter of great consequence for the good of souls. Finally, We wish this to be a special care of the Dominicans - the spread and frequent use of the Rosary among Christian people. We make this exhortation in these troublous times, following our predecessor, Leo XIII, and should it bear fruit this centenary celebration will not have been in vain. Meanwhile, as an augury of the Divine gifts and a proof of Our benevolence, We impart the Apostolic Blessing, Venerable Brethren, to you, your clergy, and your people. Given at Rome, at St. Peter's, June 29, Feast of the Prince of the Apostles, 1921, the seventh year of Our Pontificate.
Source: Fausto Appetente Die (Vatican.va)