5 And so We give thanks to God in His goodness, not only for seeing to it that this Saint would twice cast the brilliant light of his holiness over Our priestly life at moments of great importance, but also for offering Us an opportunity here at the beginning of Our Pontificate to pay solemn tribute to this wonderful shepherd of souls on this happy 100th anniversary. It will be easy for you to see, Venerable Brethren, that We are directing this letter principally to Our very dearest sons, those in sacred orders, and urging each and every one of them—especially those engaged in pastoral ministry—to devote all their attention to a consideration of the wonderful example of this holy man, who once shared in this priestly work and who now serves as their heavenly patron.
Source: Sacerdotii Nostri Primordia (Vatican.va)