In other posts we’ve looked at the guidance and wisdom carried in every religion by its local Mystery Center. The ancient mystery teachers had knowledge of the stars that, without telescopes, seems incredible to us today. The Caldeans and Persian astronomer/astrologers were well aware of the course of the sun through the zodiac and the movement of the planets. Yes, in their view of spirit as reality and physical as illusion, they placed the earth, from human perspective, in the center of the spiritual universe. They also knew that each human being begins each incarnation journey from out of the planetary spheres. Rudolf Steiner called this knowledge Etheric Astronomy. i think it relates powerfully with a healthy Eugenics.
As evolution progressed, and the sun moved from Taurus to Aries, new wisdom flowed into the Mysteries. Now the teachers learned one does not arrive at a full conception of the gradual approach of an entity out of extra-planetary spheres into the planetary and hence onto the earth sphere. No, their spirituals pictures revealed that this process leads not to a human being but rather to the human as a bull. No human beings would exist on earth if there were nothing besides this extra-planetary being that descends through the planetary sphere into evolution.
These teachers knew that the time had come when human beings must struggle against this bull-like nature with something still higher. Thus the Mysteries of Mithra came into being and spread from Persia (and perhaps from even farther east) into the Roman Empire from where it spread into eastern Europe and as far west as Spain.
This new mystery stream intended to lead humanity to overcome the aged-view of humanity’s pre-birth origin given by the ancient wisdom. What was offered outside of the Mystery Centers was the image of the bull with Mithras on top of it. Mithras was meant to be the human being who struggles to overcome the bull. Mithras was the sun force in the human being who rebelled against the merely planetary and terrestrial aspects that can only lead to the bull-human. There must be of far loftier origin than the being that was pictured according to the ancient teaching of wisdom. 
Two outcomes resulted. One, the beginnings of revolt against the revered mysteries, and two, the inner preparation for the coming of Christ who was seen as this Sun being.
Remnants of Mithraism persist in the bull-fighting in Spain and Mexico.
In the statue, note the direction of Mithra’s gaze (and compare to this blog post). Note the ‘cosmic’ animals; note where each is on the bull: the crab, the snake, and the dog. I invite you to comment on what these represent.