40 The working man, too, has interests in which he should be protected by the State; and first of all, there are the interests of his soul. Life on earth, however good and desirable in itself, is not the final purpose for which man is created; it is only the way and the means to that attainment of truth and that love of goodness in which the full life of the soul consists. It is the soul which is made after the image and likeness of God; it is in the soul that the sovereignty resides in virtue whereof man is commanded to rule the creatures below him and to use all the earth and the ocean for his profit and advantage. "Fill the earth and subdue it; and rule over the fishes of the sea, and the fowls of the air, and all living creatures that move upon the earth."(29) In this respect all men are equal; there is here no difference between rich and poor, master and servant, ruler and ruled, "for the same is Lord over all."(30) No man may with impunity outrage that human dignity which God Himself treats with great reverence, nor stand in the way of that higher life which is the preparation of the eternal life of heaven. Nay, more; no man has in this matter power over himself. To consent to any treatment which is calculated to defeat the end and purpose of his being is beyond his right; he cannot give up his soul to servitude, for it is not man's own rights which are here in question, but the rights of God, the most sacred and inviolable of rights.
Source: Rerum Novarum (Vatican.va)