Common Eldarin had another competing syntax for indicating continuous action, a “frequentative” form made by reduplicating the initial part of the verb stem; I use the term frequentative for this formation based on the gloss of the verb sisíla- “shine (frequentative)” (MC/223). This formation (perhaps) became the present continuous tense in Telerin, but did not become its own verb tense in Quenya or Sindarin, as described by Tolkien in Common Eldarin: Verb Structure (EVS2) from the early 1950s:
Reduplication often, accompanied by lengthening or fortification, or by “dynamic” lengthening of one of the base-consonants, was another feature. The latter method did not in Quenya or Sindarin become a part of normal conjugation, but was used rather to produce new independent stems with conjugations of their own. Thus mammata- “to gobble up”, or “to go on eating, gorge oneself”. But the “repetitive” form, made with reduplication; and gemination of the second basic consonant was so frequent in Quenya as to be virtually part of the system of normal basic verbs: so tutulla- “to keep on coming (and going)”. In Telerin reduplication without gemination was the normal way of forming continuous presents: mamāta- “is eating” (PE22/129).
A very similar description appeared in Quendian & Common Eldarin Verbal Structure (EVS1) from the late 1940s (PE22/95). There are numerous examples of these frequentative Quenya verbs in Tolkien’s writing from the 1940s, 50s and 60s, but the exact methods of forming these verbs that seems to vary:
- [ᴹQ.] fafarra- “repet[itive] of hunt” (PE22/112).
- [ᴹQ.] kakarra- “keep on doing” (PE22/100, 109).
- [ᴹQ.] kukumba- “keep on bowing, nod repeatedly” (PE22/112).
- [ᴹQ.] lihlikka- (†sillikk-) “sneak about” (PE22/113).
- mammata- “gobble up, devour, gorge oneself, (lit.) go on eating” (PE22/95, 130).
- [ᴹQ.] nenemma- “keep on (re-)appearing” (PE22/100).
- [ᴹQ.] ololla- “*keep on growing” (PE22/112).
- [ᴹQ.] sapsarra- “keep on rubbing, fray away” (PE22/113).
- sisíla- “shine (frequentative)” (MC/223).
- [ᴹQ.] sisilla- “glitter (white)” (PE22/113).
- [ᴹQ.] tatalla- “admire, wonder at (the excellence of)” (PE22/110).
- [ᴹQ.] †tithilla- “twinkle” (PE22/100).
- tutulla- “keep on coming (and going)” (PE22/95, 100, 130).
- [ᴹQ.] ululla- “keep on pouring” (PE22/112).
The basic pattern seems (a) suffixing the vowel a and (b) prefixing a duplicate of first two letters of the stem (CV) or a duplicating the entire stem if it is of the form VC (ululla, ololla). In addition one of the following is also done: the last consonant is lengthened (nenemma) or strengthened (kukumba), the first consonant is lengthened (mammata) or the base vowel is lengthened (sisíla). These might represent competing Common Eldarin frequentative formations or conceptual vacillations on Tolkien’s part.
In some cases the frequentative preserved older initial forms (sapsarra) but only where these older forms survived late in Quenya’s phonetic development: ps- > s- or ups- did not happen until Tarquesta (TQ). In general the frequentatives were formed (or reformed) using the “modern” basic verb stem: sisilla or sisíla from sil- rather than **sirilla and lihlikka from [ᴹQ.] hlik- rather than †sillikk- (PE22/113). Something similar happened with the perfect. However, these verbs were ancient enough that some semantic drift in their meaning might occur: mammata “(orig.) go on eating, (later) gobble up, devour”, sapsarra “(orig.) keep on rubbing, (later) fray away”.
These frequentatives are declined as weak verbs (PE22/100, 109) and resemble a-verbs in that they were originally inherently continuous in nature and did not have distinct aorist and present forms. Conceivably like a-verbs, they might adopt a present tense form in modern Quenya, especially if their semantics drifted: mammatan massa “I gobble bread (habitually)”, mammátean massa “I am gobbling bread (now)”.
Neo-Quenya: I personally find the frequentatives of the form sisilla (with lengthened or strengthened final consonants) to be the most aesthetically pleasing, but these appear mainly in the Quenya Verbal System written in the late 1940s and published in 2015. Frequentatives of the form sisíla (with lengthened stem vowels) are probably more popular, since (a) they appear in the version of the Markirya written in the late 1960s which was (b) published in 1983 so that this variation has been known to the Quenya-speaking community for much longer.
I think the two forms for frequentatives can coexist, derived from competing Common Eldarin formations along with other variations like mammata. Tolkien’s notes in EVS2 do encompass all these variations in Common Eldarin: “Reduplication often, accompanied by lengthening or fortification [of the vowel], or by dynamic lengthening of one of the base-consonants, was another feature” (PE22/129).