When to use "-que" and when to use "et"? [duplicate]

Question

For example, it is "Senatus Populusque Romanus" but it could be "Senatus et Populus Romanus".

Similarly, it is "qui ex Patre Filioque procedit" but it could be "qui ex Patre et Filio procedit"

Perhaps more drastically, in the Tantum Ergo we read:

Genitori, Genitoque
Laus et iubilatio,
Salus, honor, virtus quoque
Sit et benedictio:
Procedenti ab utroque

Basically, one line uses "-que" and the next one uses "et".

Is there any fundamental reason why one method is preferred than another? The Wiktionary entry for "-que" states that:

In archaic and official language, -que is preferred to et, from which it is distinguished by denoting a closer connection.

Is that what explains the above examples? That might be clear in the case of "SPQR" and the Nicean Credo (where the filioque is sometimes found). But it is not so evident to me in the case of the Tantum Ergo. Maybe there is more to it? Is there a "canonical" answer to this issue, or is in the end essentially arbitrary, perhaps based on taste, rhymes, etc?

Answer 1

My guess is that no-one knows the real reason for joining the -que to a preceding noun, but I believe that something similar occurs in ancient Greek (of which I know almost nothing).

I'm inclined go along with the explanation which I was taught: that Roman manuscripts were written without a break between words, and that subsequent redactors, knowing or believing that no break was observable in speech, treated the -que as an enclitic when separating the words.

I suspect that there are other enclitics used in the same way, e.g. in egomet and tutemet, but I know of no authority for that.

The different usages such as et, -que, ac, etc. depend on both style and context — sometimes, the word formed can 'look' wrong,or grate on the ear — making it hard to give a rule agreed by all authorities. To my ear, senatus populusque romanus sounds better than the alternative with et. For poetry, the metre may well determine the choice.