Mirrors have a lot of symbolic meanings, some of them spiritual.  A mirror can represent truth, self-realization, seeking, the soul or the mind.  It can represend divine intelligence.  A round mirror can represent the sun or the moon.  A round mirror can also represent
heaven, or the cosmos, while a square one represents the earth.  In Hinduism, a mirrir is a reminder that everything we see around us is just a distorted reflection of the spiritual reality.  In Buddhism, a mirror represents the Dharmakaya or Truth Body of the Buddha, having the aspects of purity .  
    In a dream, seeing a mirror may indicate the need to take a hard look at ourself.  Seeing  yourself in a cracked or flawed mirror meens you need to see yourself as you really are, flaws and all.  Seeing someone else in a mirror may mean that is a person you look up to or someone you should emulate.