English: A slightly schematized version of the forms of the Shield of the Trinity diagram found in several 13th-century manuscripts, including a 1208-1216 manuscript of Peter of Poitiers' Compendium Historiae in Genealogia Christi, the heraldic shields in Matthew Paris' "Chronica Majora" (1250-1259 A.D.), and a 1247-1258 manuscript of the writings of John of Wallingford. In two of these manuscripts, the cross is actually shown as a detailed artistic illumination of Christ on the cross, which is not attempted here.