That delicate form never had such an intense glow; if it were in the moonlight night, it would have melted away.

This profound couplet captures the overwhelming effect of extreme beauty. Mir Taqi Mir is asking a rhetorical question: Why did you need such an intense effort or energy ('tab-e-tab')? If you were simply in the moonlight, your natural radiance would be so profound that you would simply melt away. It speaks to a beauty that is so inherently captivating, it defies description or effort.