Different types of the Buddha’s teaching are associated with the capabilities of living beings. Yüan refers to the conditions with regard to living beings. This is to say that the different teachings of the Buddha are the outcome of the Buddha addressing various capabilities of sentient beings. Chih-i delineates:

“Yüan refers to the dharma of causes and conditions in the Ten Dharmarealms that form living beings. All these living beings possess the root and the nature of the Ten Dharma-realms.”

Therefore, in order to deal with different situations, the Buddha has to teach them in a manner suitable to their conditions. The mature ones get the response from the Buddha earlier. The Buddha knows whether or not beings are mature, and he responds to them accordingly. Of those who are not mature, the Buddha does not abandon them completely. Instead, he limits his teachings to the human and heavenly vehicle (Chihtsuo Jen-tien-sh’eng Shuo), which does not belong to any of the twelve divisions of scripture. To the mature ones, such as the one with the faculties of the Lesser Vehicle, the Buddha’s teaching can be classified into twelve, or nine, or eleven types. To the beings that have the potentiality of becoming bodhisattva, the Buddha bestows the teaching in twelve divisions. In general, Chih-i emphasizes that the dharma in twelve divisions is the result of the Tathāgata’s teaching as corresponding to four kinds of situations, leading to the formation of the Fourfold Teaching. (Vol. 2, Page 284)