Catechism of the Catholic Church §1887 — excerpt
The inversion of means and ends, which results in giving the value of ultimate end to what is only a means for attaining it, or in viewing persons as mere means to that end, engenders unjust structures which "make Christian conduct in keeping with the commandments of the divine Law-giver difficult and almost impossible."
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: CA 41 · Pius XII, Address at Pentecost, June 1, 1941