The mirrors used in Roman antiquity were slightly convex disks of metal, either bronze, tin or silver, that reflected light when the surfaces were highly polished.
There are about four references to mirrors in the Bible (Job 37:18; 1 Cor. 13:12; 2 Cor. 3:18 and Jas. 1:23). In ancient times, mirrors might be used for a variety of secondary purposes (some suggest in military battle, mirrors may have been used to send signals or confuse the enemy). While the idea is intriguing, there is no solid evidence that the Roman chariots were equipped with rear view mirrors!
The primary use, however, was the popular current use: to see what you look like. To see if your face is dirty; to apply make-up or jewelry; to arrange hair.
Here’s something self-evident: To use a mirror and find something that needs attention, then do nothing about it, is futile. The point is totally uncomplicated, and finds ready application: To use the Word of God and find something that needs attention in your life, but do nothing is futile.
Why read the Bible, if you’re not going to do what it says? Why come to a Bible class and learn truth for a good life, then make no effort to apply it in your life? Why listen to Bible preaching, then ignore that teaching in the way you live?
Or as James said – “For if anyone is a hearer of the word and not a doer, he is like a man observing his natural face in a mirror; for he observes himself, goes away, and immediately forgets what kind of man he was. But he who looks into the perfect law of liberty and continues in it, and is not a forgetful hearer but a doer of the work, this one will be blessed in what he does,” (Jas. 1:23-25).