Catechism of the Catholic Church §487 — 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)
What the Catholic faith believes about Mary is based on what it believes about Christ, and what it teaches about Mary illumines in turn its faith in Christ.
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
'What the Catholic faith believes about Mary is based on what it believes about Christ' — the principle that orders every chapter of the book.
Notes
Single-sentence paragraph; the following sub-heading ("Mary's predestination") has been removed.