It dawns on someone
Meaning
Someone suddenly understands or realizes something.
Origin
Imagine the first light of morning, slowly creeping over the horizon, banishing the darkness and revealing the world. That's the feeling this phrase captures: a gradual, then sudden, illumination of understanding in someone's mind. Like the sun rising, the realization finally breaks through the fog of confusion or ignorance. The word 'dawn' itself harkens back to ancient Germanic roots, meaning the breaking of light, and the phrase uses this powerful natural image to depict the moment an idea or truth becomes clear.