Pacem In Terris

I have posted this question on my Latin forum to get the grammatical aspect of it, but I want to ask it also on this forum to see if my fellow stamp collectors have encountered it before and what explanations they were given.



In 1964 Canada issued a World Peace stamp with Pacem in Terris on a ribbon around a globe. I understand pacem [sing. acc.] intending to mean "[let there be] peace"; my question is why terris [pl. abl.] rather than terra [sing. abl.]? Thanks in advance.

"Terra" means Earth or land; "Terris" refers to "lands" (plural). Since the concept of the stamp was to commemorate World Peace, it makes sense that the Latin reference is referencing "lands" as in the lands of different countries around the world, rather than just the Earth as a whole.

I'm no Latin student, but that's the way I view it anyway.

In 1963 Pope John XXIII released his encyclical ~Pacem in Terris~. Soon he died.
I`ve hated it, but it`s the so called `declinatio`, and in school we had to learn it. Terra belongs to the I. declinatio (nouns ending in -a, another example: puella=girl)
Nominativus sg. terra / Accusativus sg. terr-am / Genitivus terr-ae / Dativus terr-ae / Ablativus terr-a
Pluralis: Nominativus: terrae / accusativus terris / genitivus terrarum/ dativus terris/ ablativus terris.
II. declination: nouns ending (usually) with -o, III. declinatio nouns ending with consonants, IV declinatio -is V. decl. -us, VI declinatio -es.
-edit: sorry, I`m stupid, it`s indeed ablative, preposition `in`!!. The full sentence is:
`Pacem in terris, quam homines universi cupidissime quovis tempore appetiverunt, condi confirmarique non posse constat, nisi ordine, quem Deus constituit, sancte servato.`
Sorry again, maybe this would help.