Your Lord is seated at the Father's right hand in heaven. How then is the bread his Body? And the chalice, or rather its content, how is it his Blood?
These elements are called Sacraments, because in them one thing is perceived by the senses and another thing by the mind. What is seen has a bodily appearance; what the mind perceives produces spiritual fruit. You hear the words "The Body of Christ," and you answer "Amen."
-- Sermon 272
Prayer. O food and bread of angels, the angels take their fill of you. They are satisfied by you but never tire of you.
-- Sermon 196, 13