91 And before concluding Our letter, to you, Venerable Brethren in the Episcopate, and through you to all Our beloved sons of both clergy, We are happy to add a solemn proof of Our gratitude for the holy cooperation by which, under your guidance and example, this Holy Year of Redemption has been made so fruitful to souls. We wish to perpetuate the memory and the glory of that Priesthood, of which Ours and yours, Venerable Brethren, and that of all priests of Christ, is but a participation and continuation. We have thought it opportune, after consulting the Sacred Congregation of Rites, to prepare a special votive Mass, for Thursdays, according to liturgical rules: De summo et aeterno Iesu Christi Sacerdotio , to honor "Jesus Christ, Supreme and Eternal Priest." It is Our pleasure and consolation to publish this Mass together with this, Our Encyclical Letter.
Source: Ad Catholici Sacerdotii (Vatican.va)