Jerome

"All man's toil is for his mouth, yet his wants are never satisfied. What advantage then has the wise man over the fool? What less has the pauper who knows how to conduct himself among the living? "All that men toil at in this world is consumed by the mouth and taken to be digested in the stomach after it has been ground down by the teeth. And when a little bit has pleased the palette, it seems to create a desire, so long as it is held in the mouth. …

Commentary on Ecclesiastes ↗

Gregory the Dialogist

Moreover he is shown to burn more in his tongue, when he says: "Send Lazarus, that he may dip the tip of his finger in water, to cool my tongue, for I am tormented in this flame." The unbelieving people held the words of the law in their mouth, which they scorned to keep in deed. Therefore he will burn more there, where he showed himself to know what he was unwilling to do. …

Forty Gospel Homilies, Homily 40 ↗

Bonaventure

For this reason he says: "All the labor of man is in his mouth:" the mouth is called the initiation of desire; for he who desires, as it were, opens his mouth. Therefore, for labor to be in the mouth is to labor toward the completion of desire; whence Proverbs 16: "The soul of the laborer labors for himself, because his mouth has compelled him." And although he does this toward fulfilling his desire, it is nevertheless not fulfilled; therefore he says: "But his soul," namely that of the tenacious rich man, "will not be filled with …

Commentary on Ecclesiastes, Chapter 6 ↗