But you know that the belch of the food that has been previously swallowed yields the fragrance. For a belch is nothing other than the going forth of the wind from the mouth revealing the quality of that which has previously been swallowed. If someone should eat an apple, he has the belch which bears the quality and odor of an apple. Therefore whenever a holy man eats the “bread of life” and the flesh of Jesus, which is true food and the fruits “of the tree of life,” and drinks the wine which is reaped from “the true vine,” he has a belch which corresponds to the foods he has previously swallowed.
–from Didymus the Blind’s explanation of Psalm 44:2 (“My heart belched forth a good word”) in his Commentary on the Psalms (late fourth century)