Symbols of the Church
In Scripture, we find a host of interrelated images and figures through which Revelation speaks of the inexhaustible mystery of the Church. The images taken from the Old Testament are variations on a profound theme: the People of God. In the New Testament, all these images find a new center because Christ has become the head of this people, which henceforth is his Body. Around this center are grouped images taken "from the life of the shepherd or from cultivation of the land, from the art of building or from family life and marriage."
Source: Catechism of the Catholic Church (Vatican.va)