The horse?

Shi-fu and Layman John were walking in Westminster Square. A great swirl of traffic was passing around it, engines roaring, horns hooting. Suddenly in amongst the turning wheels John saw a pile of horse dung neatly stacked just as it had fallen and quite undisturbed by the traffic. It seemed incredible that a living horse should have passed that way in all that traffic and left so clear and neat a testimony to its presence. Layman John drew Shi-fu's attention to the unlikely pile saying, "Shi-fu, Look! Here's a pile of horse shit but where's the horse?"  Shi-fu looked at it and said, "What need have we of the horse?"