three categories of preaching ［已今当・三説］ ( i-kon-tō or san-setsu): The sutras that Shakyamuni Buddha has preached, now preaches, and will preach. A reference to a passage from the “Teacher of the Law” (tenth) chapter of the Lotus Sutra, where Shakyamuni says, “The sutras I have preached number immeasurable thousands, ten thousands, millions. Among the sutras I have preached, now preach, and will preach, this Lotus Sutra is the most difficult to believe and the most difficult to understand.” Regarding this passage, T’ien-t’ai (538–597) defines these three groups of sutras in The Words and Phrases of the Lotus Sutra as follows: “The sutras I have preached” refers to all sutras expounded before the Lotus Sutra; “the sutra I now preach” refers to the Immeasurable Meanings Sutra, the prologue to the Lotus Sutra; and “the sutras I will preach” refers to the Nirvana Sutra. According to T’ien-t’ai, the earlier sutras (the first group of sutras in the above) are provisional teachings and expounded as expedient means to lead to the truth and therefore are easy to believe. The Immeasurable Meanings Sutra says that immeasurable meanings originate from the one Law, but does not refer to the other half of the principle—that immeasurable meanings return to the one Law. Therefore, T’ien-t’ai says, it is easy to believe. He goes on to assert that the Lotus Sutra reveals the one Law and unifies all meanings with it.
The Lotus Sutra also reveals the relationship between the Buddha and disciples in the remote past. Both the theoretical and the essential teachings (respectively the first half and the latter half) of the Lotus Sutra contradict all the earlier sutras and are therefore extremely difficult to believe and difficult to understand. The Nirvana Sutra is easy to believe because it was expounded after the Lotus Sutra; that is, the teachings it contains accord with those of the Lotus Sutra, which by this time are already known. Miao-lo (711–782) states in The Annotations on “The Words and Phrases of the Lotus Sutra,” “Though other sutras may call themselves the king among sutras, there is none that announces itself as foremost among all the sutras preached in the past, now being preached, or to be preached in the future.” Dengyō (767–822) says in The Outstanding Principles of the Lotus Sutra: “All the sutras of the first four periods preached in the past, the Immeasurable Meanings Sutra now being preached, and the Nirvana Sutra to be preached in the future are easy to believe and easy to understand. This is because the Buddha taught these sutras in accordance with the capacity of his listeners. The Lotus Sutra is the most difficult to believe and to understand because in it the Buddha directly revealed what he had attained.”