five periods ［五時］ ( go-ji): Also, five periods of preaching or five periods of teachings. A classification by T’ien-t’ai (538–597) of Shakyamuni Buddha’s teachings according to the order in which he believed they had been expounded. They are as follows: (1) The Flower Garland period, or the period of the Flower Garland Sutra, which according to T’ien-t’ai was the first teaching Shakyamuni expounded after his enlightenment. The Flower Garland teaching represents a very high level of teaching, second only to the teachings of the Lotus and Nirvana period. With this teaching, the Buddha awakens his listeners to the greatness of Buddhism, though it was too profound for them to grasp. The Flower Garland period is also referred to as the Flower Ornament period or the Avatamsaka period. The Avatamsaka Sutra is the Sanskrit title of the Flower Garland Sutra. (2) The Āgama period, or the period of the Āgama sutras. Perceiving that his disciples’ capacity was not yet ready for the Flower Garland teaching, Shakyamuni next expounded the Āgama teachings as a means to develop their capacity. These teachings reveal the four noble truths—the truth of suffering, the truth of the origin of suffering, the truth of the cessation of suffering, and the truth of the path to the cessation of suffering—that free people from the six paths and correspond to the Hinayana teachings. The Āgama period is also called the Deer Park period, or the period of the sermon in Deer Park, because the Buddha preached the Āgama teachings at Deer Park. (3) The Correct and Equal period, or the period of the introductory Mahayana sutras. In this period, Shakyamuni refuted his disciples’ attachment to Hinayana doctrines and directed them toward provisional Mahayana with such teachings as the Amida, Mahāvairochana, and Vimalakīrti sutras. The Correct and Equal period is also referred to as the Vaipulya period or the Extended period. The Sanskrit word vaipulya means largeness or spaciousness. (4) The Wisdom period, or the period of the Wisdom sutras. In this period, Shakyamuni expounded a higher level of provisional Mahayana and refuted his disciples’ attachment to the distinction between Hinayana and Mahayana by teaching the doctrine of non-substantiality. The Wisdom period is also referred to as the Prajnā period because in this period the Prajnā-pāramitā, or Perfection of Wisdom, sutras were preached. (5) The Lotus and Nirvana period, or period of the Lotus and Nirvana sutras, in which Shakyamuni taught directly from the standpoint of his enlightenment, fully revealing the truth. In this eight-year interval, he expounded the Lotus Sutra and the Nirvana Sutra, the latter a restatement of the teachings in the Lotus Sutra.
According to T’ien-t’ai, the Flower Garland period lasted for twenty-one days, the Āgama period for twelve years, the Correct and Equal period for eight or sixteen years, the Wisdom period for twenty-two or fourteen years, and the Lotus and Nirvana period for eight years. In fact there is no way to verify the historical accuracy of these figures or, for that matter, of the order of the five periods. The five periods could perhaps best be described as T’ien-t’ai’s account of the process by which Shakyamuni led his disciples to an understanding of his ultimate teaching.