26 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 civic life. Just as a perfect condition of the body results from the conjunction and composition of its various members, which, though differing in form and purpose, make, by their union and the distribution of each one to its proper place, a combination beautiful to behole, firm in strength, and necessary for use; so, in the commonwealth, there is an almost infinite dissimilarity of men, as parts of the whole. If they are to be all equal, and each is to follow his own will, the State will appear most deformed; but if, with a distinction of degrees of dignity, of pursuits and employments, all aptly conspire for the common good, they will present the image of a State both well constituted and conformable to nature.
Source: Humanum Genus (Vatican.va)