[We learn in Chapter 10, The Teacher of the Dharma, that] the teacher should expound the Dharma in accordance with the three guidelines: (1) the room of the Buddha (which is having great compassion), (2) the robe of the Buddha (which is being gentle and patient), and (3) the seat of the Buddha (which is the voidness of all things). The void in the third rule refers to a mind free from all attachments. This set of three principles, with its clear-cut presentation of the Great Vehicle, is said to be the greatest doctrine of the Buddha.