Eclesiastés 10

If the iron is dull, and if it was not that way before, but has been made dull by much labor, then it will be sharpened. And wisdom will follow after diligence.

Si se embotare el hierro, y su filo no fuere amolado, hay que añadir entonces más fuerza: empero excede la bondad de la sabiduría.

If the iron be blunt, and he do not whet the edge, then must he put to more strength: but wisdom is profitable to direct.

If the ax is blunt, and one doesn’t sharpen the edge, then he must use more strength; but skill brings success.