Catechism of the Catholic Church §1405 — excerpt
There is no surer pledge or dearer sign of this great hope in the new heavens and new earth "in which righteousness dwells," than the Eucharist.
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: LG 3 · St. Ignatius of Antioch, Ad Eph. 20, 2: SCh 10, 76