Over the centuries there are many different saints who have been called an "Apostle of the Eucharist," such as St. Peter Julian Eymard, who is best known for that appellation.
One saint who is not as well known, but who shares that title, is St. Stanisław Kazimierczyk, a Polish saint who was a Patron Saint of World Youth Day in 2016.
St. Stanisław is given that title for a similar zeal for the Blessed Sacrament and how he would spend as much time as he could before the Holy Eucharist.
"Bound to the Eucharist"
Pope Benedict XVI canonized St. Stanisław in 2010 and highlighted this aspect of his life during the ceremony:
St Stanisław Kazimierczyk, a religious of the 15th century, can also be an example and an intercessor for us. His whole life was bound to the Eucharist...he was linked in a special way to the Eucharist through his ardent love for Christ present under the species of the Bread and the Wine; by living the mystery of his death and Resurrection, which is fulfilled in an unbloody way in the Holy Mass; by the practice of love for neighbor, of which Communion is a source and a sign.
St. Stanisław belonged to the Canons Regular of the Lateran, was ordained a priest in the 15th century, and spoke out against Protestant reformers in Poland who were sowing seeds of doubt among the people regarding the Real Presence of Jesus in the Eucharist.
On the website for World Youth Day in 2016, his love for the Eucharist was highlighted:
What he loved the most was the Eucharist! He prepared himself for it in silence. The Mass was for him the most important moment of the day and it was his desire that other people would not be indifferent to the richness of the graces flowing from full participation in it.
He died on May 3, 1489. His cause for canonization was revived 500 years later by St. John Paul II, and he was finally canonized by Pope Benedict XVI in 2010.
St. Stanisław, Apostle of the Eucharist, pray for us!
