Latin question -- "Agnus Dei"


I guess this is as good a place as any for a Latin question. This comes from a Facebook grammar group.

In the phrase "Agnus Dei, qui tollis peccata mundi . . . " it is obvious that the Lamb of God is being addressed. Since “agnus” is a 2nd declension masculine noun, why isn’t it in the vocative, “Agne Dei”?



It’s a direct quotation of John the Baptist’s words in John 1:29, “Ecce agnus Dei, ecce qui tollit peccatum mundi.” My guess is that it entered the liturgy as a set phrase and that by the time it dawned on people that the grammar wasn’t quite kosher, it was too late to rectify the error without seeming to be departing too far from the Biblical text. But that’s only my guess. I look forward to seeing what others, who are better informed than I am, have to say about it.

You could also query the words “miserere nobis.” Miserere is the infinitive. The imperative would be misere. In the following clause, “dona nobis pacem,” “give us peace,” the verb dona is in the imperative. Why not misere as well?



Agnus is easily construed as late Latin vocative.
Miserere is imperative from misereor.


If I remember correctly, Latin often has the nominative in lieu of the vocative; examples abound in both the classical and ecclesiastical language.


In fact–as I was reminded at yesterday’s Mass–the Gloria has not only “Agnus Dei” but “Filius Patris” (rather than “Fili”).


The previous line shows “Fili”:

Domine Fili unigenite, Jesu Christe,
Domine Deus, Agnus Dei, Filius Patris,
qui tollis peccata mundi, miserere nobis;

I can’t imagine there are metrical considerations that force the variant form for Vocative.

I’m not sure if the original Greek is available. The modern Greek version (I found on Wikipedia) shows the same variation in case. So here “Filius” and maybe “Agnus” are in Nominative in apposition to the subject.

“Oh Lord Jesus Christ, oh only begotten Son, oh Lord God, you are the Lamb of God, you are the Son of the Father, who take away the sins of the world, have mercy on us.”


since there was usually no difference between vocative and nominative conjugations for many parts of speech, the nominative was commonly used, as in English.

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