To detail the matter then, the plate in question contains three Latin scripts that translate:
"Both books were thrown into the fire."
"The Gothic one was unharmed in the flames."
"The Roman leapt out of the flame."
What is interesting to further note is that in my own research of this particular legend, I can find a few variants; one is that described above, whereby the Mozarabic missal stays in the flames unharmed, while the Roman missal leaps out of them. (Evidently, this would make the most sense contextually.) In Archdale King's Liturgies of the Primatial Sees, however, he provides an account of just the opposite, taken, he says, from the "Chronicle of Najera." In that account the Mozarabic missal leaps out (with Alfonso VI kicking it back into the flames) and the Roman book stays in the flame unharmed.
King sets out the broader background:
In Castille, Alfonso I, his French queen Agnes and the Cluniacs were in favour of the Roman rite, while the people, clergy and some of the bishops were for the Mozarabic. On 14 March 1075, we find Alfonso, together with El Cid and Simeon of Oca, at the opening of the holy ark (arca sancta) of relics at Ovideo, where the two rites were represented. The king exhorted those who were present to redouble their prayers for a solution of the liturgical controversy. It would seem that in the following year Alfonso decided to abolish the Mozarabic rite, but, perceiving the very real affection of the people for it and unwilling to cause rebellion, he suffered the formal act of suppression to remain in abeyance for two years. It is evident that there were strong manifestations of national sentiment. On 9 April 1077 (Palm Sunday), it was decided to settle the thorny question by means of a duel, which took place at Burgos. The date is attested by two texts originating from that city. One of the champions, says the Chronicle of Burgos, was a Castillian, the other came from Toledo (a knight in the service of the king), and the Toledan was vanquished. The Annales do not say who was the victor. The 'knights' knight' was defeated according to the Chronicle of Najera, which records a subsequent trial of the rival liturgies by fire...
Which, of course, brings us to the illustration in question and what we have already detailed. (The same missal, incidentally, from whence this plate came, also shows the duel between the two knights in another plate. We will show you images of this rather unique edition later today, including that plate.)
Whatever one thinks of the legend of the "trial by fire" itself, the particular point of interest, for myself at any rate, is how this legend typifies the historic tensions that have existed between other historical liturgical rites and uses and the trend toward Romanization; the tension between liturgical diversity (properly expressed) and liturgical homogoneity. It is a story, of course, which is told not only with regard to the Mozarabic tradition, but with regard to various Western liturgical rites and uses, including, not so very long ago, the Ambrosian rite. And indeed, if I might be permitted a brief bit of editorial commentary, it is arguable that this very same tendency at least in part underlay some of the suspicion and opposition that can exist with regard the freer and wider use of the more ancient forms of our liturgical books today; be they the older Roman or Ambrosian liturgical books, or be they those of the religious orders. Whatever the causes however, the effect is surely the same: the erosion of the rich tapestry that are our liturgical rites and uses and the enrichment they bring.