Scutum Fidei from AWN Pugin's Glossary of Ecclesiastical Ornament and Costume. This emblem represents the Holy Trinity - a medallion with the word Deus is in the center, surrounded by three medallions, one with the word Pater, one with the word Filius, one with a abbreviation of Spiritus Sanctus. The words non est connect each of the three outer medallions to each other, and the word est connects each to the Deus medallion. Thus, the statements:
The Father is not the Son.
The Son is not the Holy Ghost.
The Holy Ghost is not the Father.
The Father is God.
The Son is God.
The Holy Ghost is God.
Around the shield is the message Blessed be the Holy and Undivided Trinity.