Signs and symbols
1145 A sacramental celebration is woven from signs and symbols. In keeping with the divine pedagogy of salvation, their meaning is rooted in the work of creation and in human culture, specified by the events of the Old Covenant and fully revealed in the person and work of Christ.
1146 Signs of the human world. In human life, signs and symbols occupy an important place. As a being at once body and spirit, man expresses and perceives spiritual realities through physical signs and symbols. As a social being, man needs signs and symbols to communicate with others, through language, gestures, and actions. The same holds true for his relationship with God.
1147 God speaks to man through the visible creation. The material cosmos is so presented to man’s intelligence that he can read there traces of its Creator.16 Light and darkness, wind and fire, water and earth, the tree and its fruit speak of God and symbolize both his greatness and his nearness.
1148 Inasmuch as they are creatures, these perceptible realities can become means of expressing the action of God who sanctifies men, and the action of men who offer worship to God. The same is true of signs and symbols taken from the social life of man: washing and anointing, breaking bread and sharing the cup can express the sanctifying presence of God and man’s gratitude toward his Creator.
Excerpt from the Catechism of the Catholic Church