How did St. Thomas Aquinas explain the material and spoken parts of a sacrament?

St. Thomas Aquinas utilized concepts from Aristotelian metaphysics to explain the composition of a sacrament. He designated the physical material used in a sacramental rite as "matter" and the accompanying spoken words as "form."1

According to this theological framework, the material element becomes sacred and salutary only when it is joined with the proper verbal formula. This synthesis reflects Aquinas's broader philosophical view, which emphasizes the union of form and matter to constitute reality. By combining these elements, the rite functions as an effective sign—instituted by Christ—that signifies and produces grace in the recipient.123