The first mirrors were made from highly polished metals such as copper or brass. Since the 1600s, mirrors have been made from plate glass with a backing of silver covered by coatings of copper, lacquer, and paint. Mirrors do not transmit light, but reflect it. The angle at which light strikes a mirror is exactly equal to the angle at which the light is reflected back. Therefore, the image reflected is a "mirror image" of the original.
Did you know God has provided a mirror for your life? Modern glass mirrors reflect only the physical aspects of our life, but God's mirror reflects everything else: the spiritual, mental and emotional aspects of your life. A glass mirror reflects physical light whereas God's mirror reflects spiritual light. That mirror is, of course, the Word of God. The apostle James even compared the Word of God to a mirror, talking about the changes that come when a Christian "looks into the perfect law of liberty and continues in it" (James 1:25).
The mirror of the Word is like a glass mirror in one respect: It only works if you spend time looking in it.
(Turning Point Daily Devotional, 6-6-05)