Why did the Ro­mans per­ceive dark­ness, ᴛᴇ­ɴᴇ­ʙʀᴀᴇ, as a plu­ral count noun?

Question

Why did the Ro­mans per­ceive dark­ness, te­ne­brae, as a plu­ral count noun? ^{[Per­se­us cor­pus-search ref­er­ence]}

Or per­haps the bet­ter ques­tion is: what spe­cial nu­ance is con­veyed by the plu­ral te­ne­brae which would be lost were the sin­gu­lar tene­bra em­ployed in its stead? The sit­u­a­tion some­how feels dif­fer­ent than the dis­tinc­tion be­tween us­ing sin­gu­lar um­bra for shad­ow ver­sus plu­ral um­brae for shad­ows. But I could well be wrong in that.

Lewis and Short men­tion that us­ing te­ne­brae for dark­ness is “stronger than ob­scu­ri­tas”. Is the plu­ral use some­how more ab­stract or fig­u­ra­tive?

I ask be­cause this se­man­ti­cal­ly dis­tinc­tive plu­ral use for dark­ness has not mere­ly sur­vived in rare ob­scu­ri­ty but in­deed thriv­en in Lat­in’s daugh­ters, where this spe­cial plu­ral sense is still alive and well. This to me sug­gests that for the Ro­mans te­ne­brae car­ried a shade of mean­ing pow­er­ful enough to with­stand mil­len­nia of di­a­chron­ic evo­lu­tion es­sen­tial­ly un­changed.

For ex­am­ple, in French, té­nè­bres is a plu­rale tan­tum hav­ing no sin­gu­lar at all. In on­ly slight con­trast to that sit­u­a­tion, in both Por­tuguese and Span­ish the sin­gu­lar does co­ëx­ist be­side the plu­ral, but on­ly as an oc­ca­sion­al strag­gler. The plu­ral is much more com­mon in both lan­guages; it some­how seems to car­ry a heav­ier weight to my mind as a Span­ish speak­er.

The Span­ish have al­ways been con­scious of the Latin plur­al’s sense: in the Qui­jote, Cer­van­tes fa­mous­ly used the mot­to Post te­ne­bras spe­ro lu­cem in his ti­tle pages

Por­tuguese has trevas, where their dic­tio­nary notes that it’s more used in the plu­ral. Brazil­ian Por­tu­guese some­times us­es the old­er and less al­tered form tê­ne­bras in the same spe­cial way.

This same thing al­so hap­pens in the Span­ish de­scen­dant of te­ne­brae, which is ti­nie­blas, fa­mous­ly oc­cur­ring in the ti­tle of Pe­dro Almod­ó­var’s ground-break­ing Span­ish-lan­guage film, En­tre Tinieblas.

Maybe the Ro­man Cath­o­lic Church's re­ten­tion of the Latin sense for the prop­er noun Te­ne­brae (see foot­note) is part a rea­son for the per­sis­tence of the plu­ral, but it doesn't at all ex­plain the ori­gin for the strong­er, ab­stract sense which we see in Clas­si­cal Latin.

But what does?

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Foot­notes

The OED de­fines Te­ne­brae as:

The name giv­en to the of­fice of matins and lauds of the fol­low­ing day, usu­al­ly sung in the af­ter­noon or evening of Wed­nes­day, Thurs­day, and Fri­day in Holy Week, at which the can­dles light­ed at the be­gin­ning of the ser­vice are ex­tin­guished one by one af­ter each psalm, in mem­o­ry of the dark­ness at the time of the cru­ci­fix­ion. Al­so at­tribu­tive.

Answer 1

There are a couple of dozen or so words of Latin which, like tenebrae, are only ever found in the plural form. Curiously, a few of them are also plural in English translation, for example divitiae, 'riches', hiberna, winter quarters' and arma, 'arms'.

For tenebrae we would say In English ['in the] shadows', similarly referring to darkness or obscurity as an abstract noun. In looking for nuance, I doubt that the Romans would have had any more difficulty with their word than we English-speakers have with ours. I think that your question may have no logical answer : that it's just a question of custom and usage.

As for the use of both umbra and umbrae, I guess (no more than that) you might think of the singular, meaning 'shadow', as a concrete noun, sc. something that has a form that you can see — even though it has no substance. Its plural can either mean the separate shadows that you can distinguish, or be looked on as an abstract noun, like tenebrae (which is considered to indicate a deeper form of obscurity).