The moon's not seen where the sun shines.

A lesser presence, talent, or source of influence may go unnoticed beside someone or something far more powerful, brilliant, or prominent. Attention gathers around the stronger force, leaving the weaker one obscured.

The saying can also counsel modesty about rivalry: comparisons may be unfair when someone is judged beside an outstanding competitor. It describes overshadowing, not a lack of worth, and is figurative rather than a literal claim about whether the moon can be seen in daylight.

Use it figuratively when a capable person, idea, or achievement receives little notice because a more conspicuous one dominates attention. It can express sympathy for the overlooked party or lightly ironize an unequal comparison; it is not a precise statement about lunar visibility.