The Rigveda is a large collection of hymns that represents the oldest attestation of theIndo-Iranian branch of the Indo-European language family. The value of the corpus asa source of syntactic insight, however, is limited by its entirely poetic nature. Its syntaxhas been studied, but until we better understand how poetic style and grammaticalityinteract, we cannot know how much our syntactic observations of the corpus really tellus about the grammar of the language. The difficulty of investigating syntax in poetryhas not yet been properly treated. On the one hand, poetry must be intelligible, sinceit is composed and understood by the speakers of a language; on the other hand, thestructures found in poetry can differ significantly from those of usual speech, which iswhy syntacticians avoid poetry in formal studies. But for those working with limiteddata or languages attested only in poetry, drawing the line between syntax and style is anecessary step towards an accurate syntactic account. The goal of this work is to establisha distinction between grammaticality and intelligibility, and to formalize a system foridentifying which patterns in the Rigveda are grammatical and which may have beenconsciously manipulated. This system allows us to draw more reliable conclusions aboutthe syntax of the language by filtering noise out of the data.