An awakened teacher spiritually radiates the teaching which is not dependent on words or physical signs. Invisibly, it penetrates through all conditioned things even our day to day life. We can’t desire it nor can we grasp it. It comes to us having surpassed our darkness; only when we are thoroughly empty of the desire for the conditioned. This explains why many can start Zen but few if any will complete its demanding journey.
When Zen is transmitted from one culture to another the only thing that is transmitted is the culture which is reshaped by the new culture but nothing is spiritually transmitted. The unconditioned light of Mahayana (mahāyana-prabhāsa) embraces the world but the world does not know or recognize it. Those empowered by it are its worthy teachers.
Almost all traditions of Zen do not teach this although it is fundamental to the the Lanka School 楞伽宗 from which Zen arose. This is at the core of Zen’s great mystery and why it is so easy to misunderstand Zen. This light explains how the Buddha actually taught but it also explains a Buddha’s compassion.
It should be obvious that deluded beings only follow conditioned reality as it unfolds and reveals itself in their day to day life. But Zen is always pointing beyond it to what cannot be grasped by the senses. It is not about this world but points directly to what transcends it. And Zen fails miserably when it tries to minister to the needs of its parishioners who are trying to repair their broken lives and misdeeds brought about by their desires for the conditioned.