You can tell you're looking at Vishnu when you see a very handsome blue-skinned Hindu god with four arms. His dark blue color suggests that his nature is as infinite as the sky. Circling one of the fingers is a shining discus that, hurled through the air martial arts style, slices the enemies of goodness and righteousness in two. That discus also represents the spinning universe, which circles his finger like a toy.
In another hand, Vishnu wields a golden baton. He uses this to flatten our egos when we get too big for our britches. A third hand holds a conch, which is a large sea shell Hindus use like a one-note trumpet. This represents Om, the primordial sound from which universe manifested.
Vishnu's last hand holds a lotus, the symbol of purity in Hinduism. A lotus is a beautiful, delicate flower that grows in muddy ponds. Its roots extend down to the mud but the exquisite blossoms float above the water. Just so, our innermost spiritual nature is not polluted by our problems and desires and negative thoughts here in the material world. It floats above in a world of divine illumination.