Each of the twelve passages describes a saint, each of whom has a feast day. The translations and saints are as follows.

FORTASSE SOLVS QVI A FILIO SVO SVBSECVTVS PAPA HIC PIVS VIR SECRETARIVM QVOD SCRIPTVRAS ORIGENIS THEOLOGI ALEXANDRINI BLASPHEMIAS DIXIT ESSE CONVOCAVIT EVM HOMINEM QVI IN PAVPERTATE SANCTITATEM COMPLEXVS SIT HIERONYMVS ACCLAMAT

Translation: He was perhaps the only pope to be succeeded by his son. This pious man convened a council that said the Alexandrian theologian Origen’s writings were blasphemy. Saint Jerome praises him as a man of great holiness in his poverty.

This passage describes Anastasius I, whose feast day is December 19.

HIC SENATOR A SERVO SVO DE CHRISTIANITATE DEFERITVR PRO SENATV IVDICE FIDEM CHRISTIANAM ARDENTER DEFENDIT ITAQVE FIDE TECTVS MORTEM NON METVANS QVOMODO PAGANITATEM VICTVRVS SIT IESVS GLORIOSVS NARRAVIT

Translation: This senator was denounced as a Christian by his slave. He defended his Christian faith passionately before the senate as judge. Therefore, protected by faith and not fearing death, he described how glorious Jesus would conquer paganism.

This passage describes Apollonious the Apologist, whose feast day is April 18.

HIC VIR VT DICVNT FILIVS CVIVSDAM REGIS SCOTORVM ORDINATO EO AD HELVETIAM DEINDE IVIT ET ILLIC DRACONE CERTAVIT VIR PIISSIMVS POSTEA IN AD LACVM PVLCHRVM CAVERNA IPSIVS DRACONIS VITAM ASCETAE EGIT

Translation: According to legend, this man was the son of a certain Scottish king. After being ordained, he then went to Switzerland and fought a dragon there. A most pious man, he afterwards lived life as a hermit in the dragon’s cave beside a beautiful lake.

This passage describes Beatus of Lungern, whose feast day is May 9.

HIC VIR BRITANNIAE MIRACVLATOR NOMINATVS HOMINES PESTEM TERRIBILEM MORBOSQVE ALTEROS PATIENTES INTREPIDIVS CVRAVIT IS VITAM EGIT MEDICVS MAGNVS CIRCA DVNELM QVA POPVLVS CRVCEM EIVS IN PROELIVM TVLIT CARVS SANCTVS EST

Translation: This man, called the Wonder Worker of Britain, daringly tended to people suffering from terrible plague and other diseases. He lived as a great healer. Near Durham, where people carried his cross into battle, he is a most beloved saint.

This passage describes Cuthbert, whose feast day is March 20.

HIC VIR ITALIANVS AD GALLIAM ITVS EPISCOPVS LVTETIAE PRINCEPS ERAT IBI A GVBERNATORE ROMANO CAPITE SVO LEVATVS EST DECOLLATVS ET CAPVT SVVM SVBLATVS ALIQVOT MILIA VERBVM BEATVM DEI CONSTANTER PRAEDICANS AMBVLAVIT

Translation: This Italian man went to France and was the first bishop of Paris. He was beheaded there by a Roman governor. Beheaded and carrying his own head, he walked a few miles preaching the glory of god the whole way.

This passage describes Denis, whose feast day is October 9.

HIC VIR ANTIOCHENSIS MILES ANNOS LX ERAT ET CVM IMPERATORE CONSTANTINO BELLVM GESSIT. EI DEOS ROMANOS DEOS SVOS ACCIPERE INCOMPRAEHENSIBILIS, ITAQVE IVLIANVS APOSTATA EO ANNOS CX NATO DETRVNCATVM ESSE IVSSIT.

Translation: This man from Antioch was a soldier for 60 years and waged war with Emperor Constantine. It was incomprehensible to him to accept the Roman gods as his own, so Julian the Apostate ordered him beheaded when he was 110 years old.

This passage describes Eusignius of Antioch, whose feast day is August 5.

HIC EPISCOPVS ROMAE DE MAZYCIBVS NATVS TERMINALIS. AVCTOR VERBOSVS FERAXQVE LITTERARVM MVLTARVM IN QVIBVS EST DVO SVNT DE COMPARATIONE ECCLESIAE CIVITATISQVE ERAT. CVM PAPA ESSET NE LVPERCALIA PAGANA CELEBRETVR PROHIBERE CERTAVIT.

Translation: This man was the last bishop of Rome of Berber descent. Verbose and prolific, he was the author of many texts, among which is Duo Sunt, on the relationshiop of Church and State. As pope, he fought to suppress pagan Lupercalia celebrations.

This passage describes Gelasius I, whose feast day is November 21.

POTESTATEM SVAM DIVITES ET REX NON ABVTERE DEBENT HIC ANTIOCHENSIS DIXIT FAMA LOQVITVR EVM ALIQVAM PRINCIPISSAM CONSTVPRAVISSE FEMINAMQVE DE CAVTE DEIECISSE PAENITENS MISERICORDIAM SIBI PRAECATVS EST ET MIRACVLOSE IMAGO EI IGNOVIT

Translation: “The wealthy and the king should not abuse their power,” said this man from Antioch. Legend has it that he had sex illicitly with a princess, and threw the woman off a cliff. Penitent, he begged for mercy, and miraculously her likeness forgave him.

This passage describes John Chrysostom, whose feast day is September 13.

IN PHILOLOGIA CELEBRE MONASTERIO DIDICIT HIC IN LOTHARINGIA NATVS HOMO MEMORIA EIDETICA SAPIENTISSIMVS VIR TABELLAS SCIENTIAM ISLAMICAM PRODENTAS DE OFFICIO SVO LEGATI HISPANIENSIS DOMVM REFERENS IN EVROPA ARTEM MAGNOPERE AVXIT

Translation: This man, born in Lorraine, studied in a monastery renowned for scholarship. Most wise, he had a photographic memory, and bringing documents back from his post as ambassador to Spain, he spread knowledge of Islamic science greatly in Europe.

This passage describes John of Gorze, whose feast day is February 27.

IN HIBERNIA DE PARENTIBVS NOBILIBVS NATVS VIR ADMODVM PIVS VT MISSIONARIVM DEI FIAT AD BAVARIAM IN TERRA GERMANORVM IIT IBI DVCEM AD CHRISTIANITATEM TRADVXIT SED AB VXORE ILLIVS PAGANA DECOLLATVS EST

Translation: This very pious man was born in Ireland to noble parents. He went to Bavaria in Germany to become a missionary. There he converted the duke to Christianity but was beheaded by the duke’s pagan wife.

This passage describes Kilian, whose feast day is July 8.

FILIVS PAPAE PAPA IPSE FACTVS EST IN ECCLESIA ORDINE PAVLO HVMILE HABENTE TAMEN PAPA ELICTVS ELECTIO A GOTHIS SVSTENTA EST AVCTOR CASVS TERRIBILIS A VIGILIO PARATAE HVIVS VIRI IMPERATRIX THEODORA

Translation: Son of a pope, he was made pope himself. He was elected pope although he had a somewhat low rank in the church. His election was supported by the Goths. Empress Theodora was the originator of his terrible overthrow by Vigilius.

This passage describes Silverius, whose feast day is June 20.

PATRE EVM MILITEM ESSE VOLENTE HIC VIR CANONICVS FIERI OPTAVIT CISTERCIANOSQVE SE COMISIT RECTORVM CLERICALIVM CONTRA INTERCESSIONEM CIVITATIS CONSERVATOR ERAT POSTMODO BEATVS ARCHIEPISCOPVS AVARICI BITVRGIVM ELICTVS GRAVATIM AD ILLVD MVNVS ACCESSIT

Translation: Although his father wanted him to be a soldier, this man chose to become a priest and joined the Cistercians. He was a defender of clerical rights against state intervention. Later, elected blessed archbishop of Bourges, he reluctantly accepted the post.

This passage describes William of Donjeon, whose feast day is January 10.

Now notice that there is one feast day per month. Ordering by month, and using the day to extract a letter, we get:

The title, “Gratia Plena,” refers to the prayer Ave Maria. Combined with J. TRITHEMIUS, this hints the Ave Maria cipher, devised by J. Trithemius in his Polygraphia.

The original Latin passages, in the order given, represent a calendar, with each passage standing for a month. For example, the first passage has 31 words to represent the 31 days of January, the second passage has 28 words to represent the 28 days of February, etc. Picking out the saints’ feast days on this “calendar,” you get a series of words that can be decoded using the Ave Maria cipher. For example, because one of the feast days is January 10 (William of Donjeon), you pick the 10th word of the first passage to get PIUS, which represents C. The full extraction is below:

The answer is CODEX RUNICUS.