Catechism of the Catholic Church §661 — excerpt
This final stage stays closely linked to the first, that is, to his descent from heaven in the Incarnation. Only the one who "came from the Father" can return to the Father: Christ Jesus.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Also cites: Missale Romanum, Preface of the Ascension: sed ut illuc confideremus, sua membra, nos subsequi quo ipse, caput nostrum principiumque, praecessit