"Three period teaching classification." The doctrinal division of the teachings of S/akyamuni's lifetime into three periods. The Faxiang sect's 法相宗 explanation establishes the three times of the teachings of existence， the teaching of emptiness， and the teaching of the middle way. （1） The teaching of the first period （the period of the teaching of existence）， says that all existence is established due to causes， but the elements of this composition are truly existent. This is established in the a^gama sutras and other Hi^naya^na sutras. （2） The teaching of the second period， which says that the original nature of all things is empty. This is also called the "negative" period. This is the beginning of "great vehicle" teaching， as it is changing from "small vehicle" teaching. The prajn~a^pa^ramita^ sutras are examples of this teaching. （3） The teaching of the third period is that of true emptiness: the middle way is explained affirmatively through such sutras as the Avatam!saka and the Sam!dhinirmocana. This is also called the period of the "true great vehicle."