"So long as no spurious and false teachings appear in the three branches of the teaching (pariyatti, theoretical learning; paṭipatti, the practice; paṭivedha, fruits of the practice), so long will the teaching remain genuine, pure and untarnished." – S.N., Saddhammappatirūpaka Sutta Nidāna Vagga
"The great pariyatti sāsana, which is called the appearance of the tipiṭaka, is the root of the great paṭipatti and the great paṭivedha sāsanas. Only when the pariyatti sāsana is established can the other two sāsanas also be established. The burden of maintaining the pariyatti sāsana for 5,000 years is really very great. This is an age of degeneration..." - Ven. Ledi Sayadaw
"The Tipitaka appeared ~2,500 years ago so we still have at least 2,450 years left to partake in this great and challenging opportuntiy. Pariyatti has been doing its small part for the past 25 years, and shall continue to do so for centuries to come." - Pariyatti board member
The Buddha’s words quoted below were used by S.N. Goenka in the introduction of his books about the Tipiṭaka. These books (in Hindi) are availble here: Vol.1 & Vol. 2.
"There are two things, monks, which make the Truth-based Dhamma endure for a long time, without any distortion and without (fear of) eclipse. Which two? Proper placement of words and their natural interpretation. Words properly placed help also in their natural interpretation." - A.N. 1, Dukanipāta, 21
"...the dhammas (truths) which I have taught to you after realizing them with my super-knowledge, should be recited by all, in concert and without dissension, in a uniform version collating meaning with meaning and wording with wording. In this way, this teaching with pure practice will last long and endure for a long time..." - D.N. 3, Pāsādikasutta, 177
Quotes from S.N. Goenka on the importance of pariyatti:
"The study of the words of the Buddha not only deepened my practice, but also gave me an understanding of their importance in making the pure Dhamma last for a long, long time"
"(...) It is absolutely essential for people who come from different traditions to read the words of the Buddha. To be a good teacher, both Pariyatti and Paṭipatti, are important (...)"
"Sātthaṃ sabyañjanaṃ – the letter and spirit of the words of the enlightened one; sabyañjanaṃ pariyatti are the words of the Buddha. And the path, the way, the technique that he taught us to practice is sātthaṃ. So there is paṭipatti and pariyatti. Desetha dhammaṃ, give this complete Dhamma."
"The theoretical study of Vipassana meditation – pariyatti – is essential in order to orientate oneself and to understand where we are going, to comprehend what we are doing."
"(…) Sayagyi U Ba Khin used to say that pariyatti (theory) and paṭipatti (practice) must go together. Together they are like two wheels of a cart and both must be equal in size and strength if the cart is to move smoothly. With these two wheels of pariyatti and paṭipatti work diligently and travel swiftly on the path of Dhamma."
"(…) Hand in hand with the practice of meditation, however, is the theoretical foundation, like the protective golden setting for a valuable gem. The firm foundation of pariyatti provides the necessary guidance and inspiration for practitioners to take, and keep taking, proper steps on the Path."
"(…) only the experience of the truth through the systematic auto-introspection can purify the mind and eliminate the suffering. But a strong theoretical base –pariyatti- offers the necessary guidance and inspiration for the researcher of truth and for the meditators to start and continue step by step the practical path of liberation –paṭipatti."