‘Wine makes glad the heart of man' (Ps. 104:15). But you who have professed sorrow and grief should turn away from such gladness and rejoice in spiritual gifts. If you rejoice in wine, you will live with shameful thoughts and distress will overwhelm you.
The dread Mysteries, full of such great salvation, which are celebrated at every Liturgy, are also called a Thanksgiving [Eucharistia] because they are the remembrance of many benefits, and they signify the culmination of God's Providence towards us, and in every way cause us to be thankful to Him.