"a friend's eye is a good mirror"の定義と意味

What is the origin of the proverb "a friend's eye is a good mirror" and when to use it?

The origin of the proverb "a friend's eye is a good mirror" is not well-documented, however, its sentiment has been a part of Irish wisdom for centuries. The saying emphasizes the importance of trusted relationships in personal growth, as these connections can help an individual understand themselves better. While the proverb highlights the positive role of friends in personal development, it also serves as a reminder that this type of feedback must come from someone with genuine care and concern, rather than from someone who seeks to criticize without offering support.