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A Fitting Line for a Deep Metaphor

From Arne Garborg's novel Haugtussa, where the main character Veslemøy says: "There are no pills for dirty water."

The expression is often used as a metaphor for the fact that there are no simple, medical, or superficial solutions to deep, systemic, or social problems. One must clean up at the source rather than just trying to treat the symptoms afterwards.