From Section 21 of Pope Leo XIII’s encyclical Rerum Novarum, published in 1891:
The things of earth cannot be understood or valued aright without taking into consideration the life to come, the life that will know no death. Exclude the idea of futurity, and forthwith the very notion of what is good and right would perish; nay, the whole scheme of the universe would become a dark and unfathomable mystery. The great truth which we learn from nature herself is also the grand Christian dogma on which religion rests as on its foundation — that, when we have given up this present life, then shall we really begin to live. God has not created us for the perishable and transitory things of earth, but for things heavenly and everlasting; He has given us this world as a place of exile, and not as our abiding place. As for riches and the other things which men call good and desirable, whether we have them in abundance, or are lacking in them — so far as eternal happiness is concerned — it makes no difference; the only important thing is to use them aright. Jesus Christ, when He redeemed us with plentiful redemption, took not away the pains and sorrows which in such large proportion are woven together in the web of our mortal life. He transformed them into motives of virtue and occasions of merit; and no man can hope for eternal reward unless he follow in the blood-stained footprints of his Savior. “If we suffer with Him, we shall also reign with Him” [2 Tim ii.12]. Christ’s labors and sufferings, accepted of His own free will, have marvelously sweetened all suffering and all labor. And not only by His example, but by His grace and by the hope held forth of everlasting recompense, has He made pain and grief more easy to endure; “for that which is at present momentary and light of our tribulation, worketh for us above measure exceedingly an eternal weight of glory” [2 Cor iv.17].