The noun “vessel” imperfectly expresses the intended meaning of this advocation. The Latin “vas” (vessel) is used to translates the Greek term “skeuos” which does not only mean vessel but also instrument or tool. Thus, the expression “spiritual vessel” should be rendered as “instrument of the Holy Spirit." Mary is both dwelling place of the Spirit and his “agent” in the Incarnation. “With and through the Holy Spirit, the Virgin conceives and gives birth to the Son of God” (CCC 723).
The imagery of this advocation highlights this idea. The caption accompanying the symbol of the Spirit refers to the promise of the Annunciation. The Spirit will overshadow you. Mary answers the Trinity in the words of 4 Esdr. (4:14), “If I have found grace with you, send your Spirit into me. ” The picture of Mary expresses both humility (her answer to God) and grandeur (scepter in the form of a lily). The table covered with various vessels underscores the fact that Mary is the most exquisite of God’s vessels. She is a “vessel for a noble purpose” (Romans 9:21).