 These correspond to the five senses, and this is how a student turns them inward to experience what is inside of himself.See Vishnu with his four arms and they correspond to these.One hand is holding a circle (chakra) of light, one holding a conch shell for the inner sound (hold it to the ear and a sound is heard), one holding a lotus flower to refer to nectar, and finally the fourth hand is holding a metal club (mace) for the inner vibration (if you hit something with it, it vibrates like a tuning fork).