Catechism of the Catholic Church
707 Theophanies (manifestations of God) light up the way of the promise, from the patriarchs to Moses and from Joshua to the visions that inaugurated the missions of the great prophets. Christian tradition has always recognized that God's Word allowed himself to be seen and heard in these theophanies, in which the cloud of the Holy Spirit both revealed him and concealed him in its shadow.
708 This divine pedagogy appears especially in the gift of the Law. 72 God gave the Law as a "pedagogue" to lead his people towards Christ. 73 But the Law's powerlessness to save man deprived of the divine "likeness," along with the growing awareness of sin that it imparts, 74 enkindles a desire for the Holy Spirit. The lamentations of the Psalms bear witness to this.
English Translation of the Cathechism of the Catholic Church for the United States of America © 1997, United States Catholic Conference, Inc.