He less well known for something very important to liturgical studies. He is one of the most ancient witnesses to the practrice of Communoin on the tongue. Notably, Saint Leo the Great read the sixth chapter of Saint John’s Gospel as referring to the Eucharist (as all the Church Fathers did). In a preserved sermon on John 6 (Sermon 9), Saint Leo says:
“Hoc enim ore sumitur quod fide creditur” (Serm. 91.3).
This is translated strictly as: “This indeed is received by means of the mouth which we believe by means of faith. “Ore” is here in the ablative and in the context it denotes instrumentation. So then, the mouth is the means by which the Holy Eucharist is received.
If you are interested in what other Church Fathers taught about Communion on the tongue, please see:
…and if you want to learn how to properly receive Communion on the tongue, please see: