Proverbs 27:17

Iron cutting tools are made bright, and sharp, and fit for use by rubbing them against the file, or some other iron. So a man, who being alone is sad, and dull, and unactive, by the company and conversation of his friend is greatly refreshed, his very wits are sharpened, and his spirit revived, and he is both fitted for and provoked to action. The countenance is here put for the mind or spirit, whose temper or disposition is commonly visible in men's countenances.