The augment originally appears to have been a separate word, with the potential meaning of 'there, then', which in time got fused to the verb. The augment is *h₁é- in PIE (é- in Greek, á- in Sanskrit) and always bears the accent.[2][3]
Greek
The predominant scholarly view on the prehistory of the augment is that it was originally a separate grammatical particle, although dissenting opinions have occasionally been voiced.[5]
"And when rose-fingered Dawn appeared, early-born,"
Ancient Greek
In Ancient Greek, the verb λέγωlégo "I say" has the aorist ἔλεξα élexa "I said." The initial ε e is the augment. When it comes before a consonant, it is called the "syllabic augment" because it adds a syllable. Sometimes the syllabic augment appears before a vowel because the initial consonant of the verbal root (usually digamma) was lost:[6]
When the augment is added before a vowel, the augment and the vowel are contracted and the vowel becomes long: ἀκούω akoúō "I hear", ἤκουσα ḗkousa "I heard". It is sometimes called the "temporal augment" because it increases the time needed to pronounce the vowel.[7]
Modern Greek
Unaccented syllabic augment disappeared in some dialects during the Byzantine period as a result of the loss of unstressed initial syllables, this feature being inherited by Standard Modern Greek. However, accented syllabic augments have remained in place.[8] So Ancient ἔλυσα, ἐλύσαμεν (élūsa, elū́samen) "I loosened, we loosened" corresponds to Modern έλυσα, λύσαμε (élisa, lísame).[9] The temporal augment has not survived in the vernacular, which leaves the initial vowel unaltered: Ancient ἀγαπῶ, ἠγάπησα (agapô, ēgápēsa) "I love, I loved"; Modern αγαπώ, αγάπησα (agapó, agápisa).
The augment is used in Sanskrit to form the imperfect, aorist, pluperfect[a] and conditional. When the verb has a prefix, the augment always sits between the prefix and the root.[11] The following examples of verb forms in the third-person singular illustrate the phenomenon:
In J. R. R. Tolkien's Quenya, the repetition of the first vowel before the perfect (for instance utúlië, perfect tense of túlë, "come") is reminiscent of the Indo-European augment in both form and function, and is referred to by the same name in Tolkien's grammar of the language.
^Clackson, James. 1994. The Linguistic Relationship Between Armenian and Greek. London: Publications of the Philological Society, No 30. (and Oxford: Blackwell Publishing)
Bibliography
Burrow, T (2001). The Sanskrit Language (2001 ed.). Motilal Banarsidass. ISBN81-208-1767-2.
Clackson, James (2007). Indo-European Linguistics. Cambridge. ISBN978-0-521-65313-8.
Fortson, Benjamin W (2010). Indo-European Language and Culture (2010 ed.). Wiley-Blackwell. ISBN978-1-4051-8895-1.