‘The purpose of awakening to the old stories of the Patriarchs of Zen is to modify gradually what you have understood and thought up to now, under the guidance of a Zen Master. Evenif the Buddha you have known up to now is endowed with the distinguishing marks, radiate light, and has, like Sakyamuni and Amita Buddha, the virtue of preaching sermons and bringing benefits to the people, you must believe it if the Zen Master tells you that the Buddha is a toad or an earthworm. You will have to give up the beliefs you have held up to now. But if you seek the Buddha’s marks, his radiance, and the various virtues associated with him on the earthworm, you still have not modified your arbitrary views of the Buddha. Just recognize as the Buddha what you see now before your eyes. If you follow the words of the Zen Master and turn from deluded views and attachments, you will naturally accord with the Buddha Way.’ (Shobogenzo Zuimonki)
I don’t recall any teacher I have worked with telling me that the Buddha was a toad or an earthworm, but as usual, Dogen makes a very concrete analogy do his work for him. The key line is the penultimate sentence.