As we prepare for the rededication of our land to our Lady, I elucidate a piece of Latin which is circulating on the Internet in mysteriously garbled forms. Here is the line:
DOS TUA I VIRGO PIIA / HAEC I EST QUARE I REGE MAIRIA
It is a typical medieval hexametre; forget all you ever knew about 'longs' and 'shorts' and go by rhythm. I have inserted the red bits not as letters but as metrical dividers. I divides the line into its six 'feet'. / is the 'caesura', the midline break. As so commonly in such medieval verses the syllables just before the caesura rhyme with the syllables at the end of the line, in this case -IA. Further examples of such versification occur on the tomb of Richard II in Westminster Abbey. (The term 'Leonine' is commonly attached to such verse.)
Modern punctuation might give us this:
Dos tua, Virgo pia, haec est; quare rege, Maria.
In English:: O pious Virgin, this is your dowry, wherefore, O Mary, rule [it].
This inscription is recorded as having been on a picture which hung above an Altar in the English College in Rome until the Napoleonic Episode. It showed a king and queen kneeling and offering England to our Lady; it is to be her dowry, and the offering is made through the hands of S John Baptist (King Richard II's patron and one of the most popular Saints until S Joseph somewhat encroached upon his cultus). The Altar above which it stood (in what had, of course, been the old royal English Hospice until it was converted into the Venerable English College) was that of S Edmund the Martyr.
[Sources: Edmund Waterton's Pietas Mariana Britannica (1879); and BL Harleian ms 360]
The most helpful explanation I know is in Dillian Gordon's Making and Meaning THE WILTON DIPTYCH (1993; reprinted 2001). She describes that great Diptych, in our National Gallery, which also shows King Richard II dedicating England to our Lady as her dowry. In the course of investigating the Diptych, Gordon also provides the background of the now lost Roman picture which we are discussing this morning.
Gordon explains the choice of King Richard's favourite Saints; and invites us to look carefully at the orb above the white banner with the red cross. It shows, very probably, England as 'a green island with trees on the horizon and a white castle with two turrets and black windows'. It is surrounded by a sea which was originally silver leaf (I wonder if W Shakespeare ever saw this?)
You can't look at the picture in Rome because the Enlightenment so wisely destroyed it for you, but if you want to enter into the spirit of the Rededication, you can go and look at the Wilton Diptych. If yiu felt up to all the hassle of getting into Westminster Abbey, you could visit King Richard's and Queen Anne's tomb.
Gordon's book is well worth buying.