CCC 1960 The precepts of natural law are not perceived by everyone clearly and immediately. In the present situation sinful man needs grace and revelation so moral and religious truths may be known “by everyone with facility, with firm certainty and with no admixture of error.”1 The natural law provides revealed law and grace with a foundation prepared by God and in accordance with the work of the Spirit.
1 Pius XII, Humani generis: DS 3876; cf. Dei Filius 2: DS 3005.