Nandi bull is the Vahana or the living transport of Lord Shiva. As a matter of submission and humility, the tail is tucked in, and the feet and face are in repose. It is a charging bull made tame by Lord Shiva. Nandi represents a devotee (of Shiva) whose passions are under control and whose devotion to Shiva is perfect. Nandi is Shiva’s closest accomplice because he is the essence of receptivity. Before you go into a temple, you must have the quality of Nandi – to simply sit. You are not trying to go to heaven, you are not trying to get this or that – you go inside and simply sit.