32 Let those children of sloth, the Manicheans, make answer; who without labouring themselves eat up the labourers' fruits: who welcome with smiling faces those who bring them their food, and return curses instead of blessings. For when a simple person brings them anything, “Stand outside a while,” says he, “and I will bless you.” Then having taken the bread into his hands (as those who have repented and left them have confessed), “I did not make you,” says the Manichee to the bread: and sends up curses against the Most High; and curses him that made it, and so eats what was made. If you hate the food, why did you look with smiling countenance on him that brought it to you? If you are thankful to the bringer, why do you utter your blasphemy to God, who created and made it? So again he says, “I sowed you not: may he be sown who sowed you! I reaped you not with a sickle: may he be reaped who reaped you! I baked you not with fire: may he be baked who baked you!” A fine return for the kindness!
Source: Catechetical Lectures (New Advent)