There's none so blind as those who will not listen.

The line adapts a long-standing proverb (“none so blind as those who will not see”), shifting the emphasis from visual refusal to auditory refusal. Read this way, “blindness” becomes a metaphor for self-imposed ignorance: a person may have access to information, testimony, or warning, yet remain effectively “blind” because they refuse to listen. The phrasing also implies an ethical dimension—listening is not merely passive reception but a chosen openness to other people and to inconvenient facts. As a maxim, it critiques stubbornness, denial, and willful misunderstanding, suggesting that the greatest obstacle to insight is not lack of evidence but resistance to hearing it.