That will settle the Manichees!
There is an amusing story told about St. Thomas Aquinas I have always liked. Once, friar Thomas was invited to dine at the table of the King of France, Louis IX, who would eventually be canonized a saint, too. Brother Thomas, fell silent as the meal and conversation continued around him, lost in thought.
Then, suddenly, Thomas exclaimed, “That will settle the Manichees!” The other guests stared aghast at the apparently rude outburst. But the king recognized that the brilliant Dominican friar had been distracted wrestling with a philosophical and theological difficulty, apparently trying to answer those who view the material world as evil and deriving from an evil principle (as Manichees do). This is an issue dear to the heart of Dominicans as it was against just such heretics that St. Dominic set about his task of preaching that eventually led to the foundation of the Order of Preachers. King Louis accordingly called for scribes to take down the insight Brother Thomas had come to, lest it be forgotten.
Today is the feast day of St. Louis of France, host to St. Thomas Aquinas, and one who saw and supported him in his academic ministry. Ora pro nobis.