Taken from the introduction to the Guide. page xi
From the commentary by Dhammapala
'If it is asked,
‘How can it be known that the “Guide-Treatise” is what was
uttered by a principal disciple and approved by the Buddha ? (it
can be answered that it is) because it is a text ;
for there is no other
criterion beyond a text, and any text not in contradiction (when
examined) under the four Principal Appeals to Authority (§120) is
the criterion. And the “Guide-Treatise” has, like the “Disclosure
of the Pitakas” (Petakopadesa), come down (to us) by way of the
unimpeachable succession of teachers (see DA Introduction).—If
that is so, then why is its source9
not given ? For a source is
given in the cases of the Subha Sutta (D. Sutta 10), the Anangana
Sutta (M. Sutta 5), the Kaccdyana Samyutta (S. iii, 9 ?), etc., which
were uttered by disciples.—That is not always so in the case of
disciples’ utterances and even in the case of some of the Buddha’s
utterances; for no source is given in the cases of the Patisambhiddmagga and the Niddesa10 or in the cases of the Dhammapada and
the Buddhavamsa, so that is no criterion; and that is how it should
be regarded here too. And then any source is itself always the
utterance of the custodians of the Sutta and Vinaya, the Elders
Upali and other principal disciples,
and so that too is uttered by
principal disciples. And anyway why this investigation about a
source, since there is no one else to whom to ascribe it except the
Elder ? What needs investigating here is only the meaning (in
order to see) that it does not conflict with the texts. Besides, as a
method of detailing (samvanriana) the meaning of texts, this work
has no more need of a separate source than have the Patisambhidamagga or the Niddesa
(Netti A., p. 3)