13 ways of looking at my guru: The thirteenth among the twelve

Rudolf Steiner, from a lecture given September 21, 1909:

"We must acknowledge the role of the great lodge of the twelve bodhisattvas in governing the entire evolution of the Earth. On a higher plane, the bodhisattvas manifest the concept of 'teacher' as we apply it on lower levels of existence. As teachers, they inspire faculties that human beings must acquire.
What is the source of the content the bodhisattvas proclaim from epoch to epoch? If you could behold the circle of the twelve bodhisattvas in the great spirit lodge, you would discover a thirteenth being sitting in their midst. This being, who cannot be called a teacher in the same sense as the twelve, radiates the substance of wisdom itself. The twelve bodhisattvas in the great spirit lodge sit around a central point, immersed in contemplation of the great being who exudes the wisdom that they are to incorporate into earthly evolution. The thirteenth being exudes what the other twelve will teach. The twelve are the teachers and inspirers who proclaim the presence of the thirteenth from epoch to epoch; the thirteenth is the very substance of their teaching. He is the ancient rishis' Vishva Karman, Zarathustra's Ahura Mazda, and our Christ, the leader and guide of the great bodhisattva lodge. Thus the entire choir of the bodhisattvas proclaims the doctrine of the Christ, or Vishva Karman....
The task of the thirteenth is not to present teachings but to be the teachings, to be spiritual substance itself.
What is Vishva Karman, Ahura Mazda, the Christ, in his true form, but the divine Word of creation? Strange as it may seem, Zoroastrianism tells us that Zarathustra was initiated so that he could perceive, standing behind the light, not only Ahura Mazda but also Honover, the divine Word of creation--the Veda--that was to descend to Earth. During the baptism in the Jordan, this Word descended into an individual human ether body for the first time. The spirit Word--the Veda--that had been preserved since Lemurian times streamed down from the heights into the ether body of the Nathanic Jesus. When the baptism was completed, the Word--the Veda--had become flesh....
The element that had been denied human beings for so long because of their involvement with Lucifer first became flesh, descending to Earth and living on Earth, in a single personality. This being is the great ideal to be emulated by all those who slowly learn to understand his nature. This is why our earthly wisdom must follow the example of the bodhisattvas, whose task is always to proclaim the thirteenth in their midst. We must apply all our spiritual science--our wisdom, our knowledge, and the results of spiritual research--to comprehending the being and nature of Vishva Karman, Ahura Mazda, the Christ."