The world is a grindstone and life is your nose.

Allen’s quip casts life as abrasive and indifferent: the “world” is a grindstone that will wear you down regardless of your wishes, while your “nose” stands for the vulnerable self that gets pressed against it. The joke works by yoking a familiar proverb-like setup (“the world is…”) to an unexpectedly bodily, slightly grotesque image, turning existential complaint into punchline. It also reflects Allen’s characteristic radio-era cynicism and wisecracking fatalism: experience polishes, flattens, or injures you, and the only agency implied is whether you meet the grindstone head-on or are forced into it. Humor becomes a way to acknowledge hardship without sentimentality.