a friend's eye is a good mirror

proverb A friend can impart an honest opinion to one. I don't know about this outfit on me. Let me ask Maria what she thinks—a friend's eye is a good mirror. I always ask Tom to read my writing before submitting it. A friend's eye is a good mirror, and he'll always tell me if it needs more work. I know that a friend's eye is a good mirror, so be honest—what do you really think of my new haircut?