Horace, Ars Poetica, line 231 ff.

Context: light and bawdy verses ill become tragic poetry

Effutire leuis indigna tragoedia uersus,
ut festis matrona moueri iussa diebus,
intererit Satyris paulum pudibunda proteruis.

Translation: Tragic drama disdaining the blabbing of light verse,
like a gentlewoman dancing by command on festal days,
[each]will be somewhat shamed among ribald Satyrs.
moveri: isn’t this the present passive infinitive? I don’t have a rationale for this.

intererit: I have made this the verb for both tragoedia and matrona

indigna: I parse this as nominative, singular, feminine. I don’t understand the grammar of this adjective.

Basically, you have this right.

indigna – agrees with t_ragoedia_ and is complemented by effutire: “unworthy/undeserving to babble”

moveri – this is Horace’s comical way of expressing “to dance”. Lewis & short glosses this specific passage as “dance,” giving only one other instance of a similar usage, also from Horace. Using the passive perhaps reinforces the idea that the activity is involuntary. The image is of a proper, middle-aged (and perhaps somewhat overweight) lady reluctantly forced to move her body in a somewhat licentious way. “Matron” would be a good English translation for matrona here.

intererit – the subject is tragoedia, not matrona. matrona is just a simile. No need for “each.”

pudibunda – probably better “ashamed” than “shamed”.

Just to make sure, hlawson: you did realize levis versus is acc.pl.? Perhaps you heard as you read it that levis has long i.

iussa moveri: ordered to be put into motion i.e. to put herself into motion, to dance. Such activity is infra dig (indigna) for a matrona, just as effutire levis versus is for lady Tragoedia.

Thanks to both mwh and Hylander for the comments on my query. I did read levis . . . versus, as respectively modifier and noun, both accusative plural. I had to be away from computers for a few days, which explains the tardy reply.

I think I need some more dictionary work on ut and indign-us, -a, -um. I believe much of my difficulty with these lines came from lack of experience with these words as Horace uses them here. It seems to me that Horace often intends word meanings outside my knowledge.

If I understand rightly, then

ut festis matrona moueri iussa diebus,

somewhat resembles

like a patient etherized upon a table

Yes that’s it. Or like a tedious argument of insidious intent. But yours is syntactically closer.

Horace does tend to use words in unusual ways. But ut “like” is common enough in introducing a comparison (cf. sic-ut), while indigna is a little more interesting.

Oh, do not ask, “What is it?” There will be time for a hundred indecisions.