Catechism of the Catholic Church §966 — English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va (official text, quoted at the cited paragraph)
"Finally the Immaculate Virgin, preserved free from all stain of original sin, when the course of her earthly life was finished, was taken up body and soul into heavenly glory, and exalted by the Lord as Queen over all things, so that she might be the more fully conformed to her Son, the Lord of lords and conqueror of sin and death." The Assumption of the Blessed Virgin is a singular participation in her Son's Resurrection and an anticipation of the resurrection of other Christians:
In giving birth you kept your virginity; in your Dormition you did not leave the world, O Mother of God, but were joined to the source of Life. You conceived the living God and, by your prayers, will deliver our souls from death.
This text is under copyright; the cited paragraph is quoted for study, with a link to the full document. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Why Pitre cites it
Mary 'exalted by the Lord as Queen over all things' — the Catechism quoting Pius XII on the Assumption and queenship.
Notes
First sentence is CCC quoting Lumen Gentium 59 (cf. Pius XII, Munificentissimus Deus, DS 3903; Rev 19:16). The indented Byzantine troparion for the Dormition is part of §966. Trailing sub-heading (". . . she is our Mother in the order of grace") removed; footnote numbers removed.