Glare is like a "grammatical error" in the language of light and shadow—it is not an inherent flaw of light itself, but a result of improper human control over light. In lighting design, understanding the formation mechanism of glare is akin to mastering the "rules of light's boundaries": we must not only establish a comfortable visual order through anti-glare technologies, but also know how to utilize the "visual impact" of glare in a limited way in artistic and commercial scenarios. From causing physical discomfort to serving as an aesthetic tool, the duality of glare precisely proves that the language of light requires not only "expression" but also "restraint"—finding a balance between "visibility" and "comfort" for every beam of light is the highest realm of light and shadow narrative.