From Leo XIII’s encyclical Humanum genus, of April 20, 1884:
In like manner, no one doubts that all men are equal, one to another, so far as regards their common origin and nature, or the last end which each one has to attain, or the rights and duties which are thence derived.
But, as the abilities of all are not equal, as one differs from another in the powers of mind or body, and as there are very many dissimilarities of manner, disposition, and character, it is most repugnant to reason to endeavor to confine all within the same measure, and to extend complete equality to the institutions of civil life.
(Rev. John J. Wynne, S.J., ed. The Great Encyclical Letters of Pope Leo XIII [New York: Benziger Brothers, 1903], p. 98).
Plinio Corrêa de Oliveira, Nobility and Analogous Traditional Elites in the Allocutions of Pius XII: A Theme Illuminating American Social History (York, Penn.: The American Society for the Defense of Tradition, Family, and Property, 1993), Documents V, p. 479.