Ad Diem Illum Laetissimum §26

²⁶ And that heavenly graces may help Us more abundantly than usual during this year in which We pay her fuller honour, to attain the imitation of the Virgin, and that thus We may more easily secure Our object of restoring all things in Christ, We have determined, after the example of Our Predecessors at the beginning of their Pontificates, to grant to the Catholic world an extraordinary indulgence in the form of a Jubilee.