One of the surest evidences of friendship that one individual can display to another is telling him gently of a fault. If any other can excel it, it is listening to such a disclosure with gratitude, and amending the error.

Bulwer-Lytton frames true friendship as an ethical practice rather than mere affection. The “surest evidence” of friendship is the courage and care to point out a friend’s fault “gently”—a balance of honesty and tact that aims at the other’s good, not at superiority or humiliation. He then elevates an even rarer virtue: receiving criticism with gratitude and actually changing. The quote thus treats friendship as mutual moral improvement, where candor is a gift and humility is the proper response. It also implies that relationships built only on flattery are fragile, while those that can withstand correction are deeper and more trustworthy.