The pestle was the grinding instrument used with a mortar for crushing grain, spices, or other materials. Proverbs 27:22 uses it in a striking metaphor: even if you pound a fool with a pestle in a mortar among the grain, you won't remove his folly. The image suggests vigorous, repeated pounding—the kind of forceful action needed to break down grain. Yet the proverb's point is that folly is even more stubborn than grain; it cannot be beaten out of someone through punishment alone. This reflects wisdom literature's understanding that true change requires more than external force.