Mimamsasutra 43.1.1

43.1.1

atha navamādhyāyasya tṛtīyaḥ pādaḥ |
(prathame- vikṛtau mantragatavrīhyādiśabdānāmūhādhikaraṇe sūtre 1-2)|
prakṛtau yathotpattivacanamarthānāṃ tathottarasyāṃ tatau tatprakṛtitvādarthe cākāryatvāt ||

Now begins the third quarter of the ninth chapter.
(In the first topical section on the adaptation of words such as “rice” occurring in mantras in the ectypal ritual, aphorisms 1–2):
As in the archetypal ritual things are mentioned in accordance with their origin, so in the subsequent rite, because it has that as its archetype and because an entity is not an effect [of the text].