Beatrice and Dante in Paradiso, engraving by Gustave Doré
I say that, following Arabic usage, her most noble spirit departed from us in the first hour (6am) of the ninth day of the month (the nineteenth): and following Syrian usage she departed from us in the ninth month of the year (June), because their first month is First Tixryn which is October to us: and following our usage she departed from us in that year of our era, that is of the years of Our Lord, in which the perfect number (ten) had been completed nine times in the century in which she lived in this world, and she was a Christian of the thirteenth century (1290).That the number has resonance with the final word of the book's title (nove and nuova, the new life) is also worth noting.
As to why this number was so closely tied to her, this might provide a reason: since, following Ptolemy and following Christian truth, there are nine revolving heavens, and following common astrological opinion these heavens must affect what is beneath them according to their aspects together, this number was closely linked to her in order to show that at her birth all the nine revolving heavens were in perfect accord.
This is one reason: but thinking more subtly, and following infallible truth, this number was she, herself: I say it symbolically, and I will explain it so. The number three is the root of nine, because, without any other number, of itself it creates nine, as can be clearly seen in that three times three is nine. Therefore if three is of itself the only maker of nine, and the only maker from itself of miracles is threefold, that is the Father and the Son and the Holy Spirit, who are three and one, that lady was accompanied by this number nine to reveal that she was a nine, that is a miracle [emphasis added, the translation of the title of this post], of which the root, that is of the miracle, is solely the miraculous Trinity. Perhaps a more subtle person could find in it a more subtle reason: but this is the one that I see, and that pleases me most.