As you can see, it's quite unique. In fact, I've never seen anything like it in all my travels. The Blessed Mother is holding the Eucharist Host and Chalice while the Holy Spirit (in the form of a Dove) hovers above her halo.
Now I don't know about you, but I've only ever seen the Blessed Mother holding the Child Jesus (who in turn holds the Eucharist). This depiction is very "priest-like" at first glance. I became so intrigued that I began hunting down who commissioned the window, why they chose this pose, and if there was any other example of this "set-up" anywhere else in the world! To make a long story short, no one was able to really help. I went to priests, figured out where the window was created (they weren't helpful with info - at all), and spoke with a few theologians who were all just as baffled by this depiction as me.
Fast forward a year and a half later, and I come across Pope John Paul II's ECCLESIA DE EUCHARISTIA. Chapter Six deals solely with the Blessed Mother's vital part in bringing the Eucharist into being. She was, in fact, the VERY FIRST TABERNACLE. When she said "Fiat" to God, she accepted into her womb the physical presence of Jesus. That is why when we say "Amen" after the priest says "The Body of Christ" we echo Mary's original, trusting acceptance of this doctrine of faith.
As she made her way to visit her pregnant cousin, Elizabeth, she in effect became the VERY FIRST EUCHARIST PROCESSION! She was a living monstrance and through her, the Presence of God could be felt. This is why both Elizabeth, and the child she carried within her (St. John the Baptist) were overcome with joy as the Blessed Mother approached. Oh how beautiful that first greeting must have been. "Blessed art thou amongst women, and blessed is the fruit of thy womb!" Indeed, St. Elizabeth, indeed!
All of the sudden, the stained glass window came to mind. This realization was a kiss from the Holy Spirit. The Blessed Mother wasn't being portrayed as a priest. She was being portrayed as the original bearer of the Most Holy Eucharist! She was being depicted in her role as the Mother of the Eucharist! Oh, what a beautiful and wonderful gift to understand this! To think I had never given the Blessed Mother's role in the Most Holy Eucharist a thought! Shameful! But this grace is a blessing as my participation in the Eucharist will always echo the Blessed Mother's "fiat" in a more profound way.
I'm so thankful for this that I'll post another picture, this time of the Blessed Mother depicted more concretely as the 1st Tabernacle of Christ... the first Eucharistic Procession. Fiat!