5 This affectionate union, varying in intensity according to time and place, and differing in its mode of expression, seems in the designs of Providence to grow stronger as the times grow more difficult for the cause of sound teaching, of sacred discipline, of the liberty of the Church. We have examples of this in the Saints of other centuries, whom God raised up to resist by their virtue and wisdom the fury of persecution against the Church and the diffusion of iniquity in the world. One of these We wish especially in these Letters to commemorate, now that the eighth centenary of his death is being solemnly celebrated. We mean the Doctor Anselm of Aosta, most vigorous exponent of Catholic truth and defender of the rights of the Church, first as Monk and Abbot in France. and later as Archbishop of Canterbury and Primate in England. It is not inappropriate, We think, after the Jubilee Feasts, celebrated with unwonted splendor, of two other Doctors of Holy Church, Gregory the Great and John Chrysostom, one the light of the Western, the other of the Eastern Church, to fix our gaze on this other star which, if it "differs in brightness" (I. Cor. xv. 41) from them, yet compares well with them in their course, and sheds abroad a light of doctrine and example not less salutary than theirs. Nay, in some respects it might be said even more salutary, inasmuch as Anselm is nearer to us in time, place, temperament, studies, and there is a closer similarity with our own days in the nature of the conflicts borne by him, in the kind of pastoral activity he displayed, in the method of teaching applied and largely promoted by him, by his disciples, by his writings, all composed "in defense of the Christian religion, for the benefit of souls, and for the guidance of all theologians who were to teach sacred letters according to the scholastic method" ( Breviar. Rom. , die 21 Aprilis). Thus as in the darkness of the night while some stars are setting others rise to light the world, so the sons succeed to the Fathers to illumine the Church, and among these St. Anselm shone forth as a most brilliant star.
Source: Communium Rerum (Vatican.va)