The “discerning Eye” (Line 2) symbolizes good judgment––it’s what allows the speaker to separate the “Madness” from the “divinest Sense” (Line 1). Senselessness and sensibleness can be tricky to tell apart, so a person has to cultivate a keen view of the world. Through the eye, the person sees what’s logical and irrational. They understand that bewildering behavior can be reasonable and that rational behavior can be ridiculous.

As the eye is a symbol, a person doesn’t have to literally see to see sense from “madness.” The canonized 17th-century English poet John Milton battled eyesight issues throughout his life and eventually lost the capacity to see. In his works, Milton argued that he possessed a deeper, inner light that allowed him to see the folly of his contemporaries who criticized his views on censorship, divorce, politics, and an array of other issues. Thus, good judgment isn’t necessarily something someone can acquire or learn: It’s a gift that a person possesses or lacks. Like Milton, Dickinson’s speaker has the elusive “discerning Eye,” so they know senselessness when they see it, and they know sense when they see it.