In his great encyclical letter Libertas Praestantissimum, Pope Leo XIII explains that it is not man’s place to dictate to God what man owes Him, but rather humbly and obediently to receive from God the law that must be followed if we are to please Him and attain the happiness for which He created us:
If the human mind be so presumptuous as to define the nature and extent of God’s rights and its own duties, reverence for the divine law will be apparent rather than real, and arbitrary judgment will prevail over the authority and providence of God. Man must, therefore, take his standard of a loyal and religious life from the eternal law; and from all and every one of those laws which God, in His infinite wisdom and power, has been pleased to enact, and to make known to us by such clear and unmistakable signs as to leave no room for doubt. And the more so because laws of this kind have the same origin, the same author, as the eternal law, are absolutely in accordance with right reason, and perfect the natural law. These laws it is that embody the government of God, who graciously guides and directs the intellect and the will of man lest these fall into error. (Libertas 17)
We see in these luminous words the confidence of a pope and of a church convinced of the reality and primacy of God, the existence of absolute truth, the ability of reason and faith to know that truth—and the ability of even fallen men to live according to that truth with the help of God’s grace (as Pope Leo develops at greater length elsewhere in the same encyclical, and as John Paul II was to do so masterfully in Veritatis Splendor).

