The “chronogram” is a phrase or a verse in which some letters, corresponding to Roman numerals (larger than the whole context), indicate the date of the event to which the phrase or the verse refers.
In the case of the memorial known as “Madonna degli Scolari”, the inscription refers to the realization of the statue of the Virgin Mary, which occurred under the pontificate of Pope Clement X (Emilio Bonaventura Altieri, 1590-1676, Pope since 1670).
VT SVB PRAESIDIO FAVSTOS PIA VIRGO SCHOLARES
BONONIAE FOVEAS AD SVA VOTA DIV
SIC PETRVS ERDEODI COMES DE GENTE CROATA
ET LEGISTA PRIOR DEDICAT HANC STATVAM
QVO CLEMENS X SEDIT PIE GVBERNANS
In the first four lines, the highest letters represent normal initials, the first name and the title.
In the fifth line there is the writing “ANNO” (YEAR), and it is precisely in the last line that the chronogram is hidden and it refers to the year of the realization of the work: 1672.
“Because with Your intercession, O Pius Virgin, may You always bless and help the students of Bologna until the fulfilment of their vows. Peter Count of Erdeodi, of the Croatian Nation and Prior of the Legisti, dedicates this statue the year in which Clement X acceded to the sacred throne (in 1670).
The text was thus translated into the volume “Le iscrizioni dell’Archiginnasio” (Zanichelli, 1962), but the two authors, Gherardo Forni and Giovanni Battista Pighi, had not noticed the hidden chronogram and had interpreted the text of the last line as the year of election of Pope Clement X, which is 1670.
The discovery of the chronogram is due to the scholar Giovanni Paltrinieri who understood that in the last line there is the reference to “a year” of the pontificate, that is 1672, the date of construction.