When I first became acquainted with Persian some years ago, two grammatical features seemed unusual to me from an Indo-European perspective. One was the ezafe construction, which I eventually learned was the product of contact with Caucasian languages. But the other was the formation of the present tense with a prefix me‑ (indicative) or be‑ (subjunctive) followed by the verb stem and personal endings. In his chapter ‘Dialectology and Topics’ in Routledge’s The Iranian Languages pp. 24–25, Gernot Windfuhr offers a fine summary of the changes that produced the modern Persian system of tenses, which not only clarifies the origin of me‑ and be‑, but shows that Persian has returned to the same five-member tense/aspect system that Iranian (like Greek) started off with.
The history of the parameters and axes of the verb systems from Old Iranian to Modern Iranian shows a cycle from a five-member quincunx to varying Middle Iranian systems back to a quincunx. The development is shown here with the example of Persian.
The inherited fundamental and primary verbal parameter of the Early Old Iranian system is triple aspect which intersects with the binary tense parameter of present and past (marked by the augment a‑). It is centered on the perfective aorist:
Early Old Iranian Present Past Imperfective PR a-PR “Present system” Perfective AOR “Aorist system” Resultive-stative PF (a-PF) “Perfect system”
In time, this triple aspect system was reduced to forms of the “present” system, i.e. imperfect present and imperfective past, leaving only a few forms of the aorist and the perfect. With their loss, the highly complex inherited system was reduced to a single imperfective stem, distinguishing present vs. augmented imperfect: PR vs. a-PR.
Concomitantly, however, the vacated aorist and perfect ranges of the system were partially filled by the innovation of a new perfective system based on the adjectival completive participle in -tá plus the present and past copula, with both intransitive and transitive verbs.
In Middle Persian, the resulting four-member system of two imperfective and two perfective forms was extended by replacing the copula with the stative verb ēst‑ ‘to stand’. The outcome was a six-member system with a triple aspect axis and a binary tense axis:
Middle Persian Present Past Imperfective raw‑ (a-raw‑) present imperfect (later lost) Perfective raft COP raft būd COP preterit past preterit Resultive-stative raft ēst‑ raft ēstād COP perfect pluperfect
In addition, the adverb hamē lit. ‘forever’ expressed ongoing and progressive action as well as continuing state, while its pendant bē (homophonous with the adverb bē ‘out, away’) expressed the singularity of an event in present and past and assumed inchoative or future connotation with the present stem.
In Early New Persian, (ha)mē‑ and bē‑ were continued, but the periphrastic resultative ēst‑ forms were replaced by extended forms based on the verbal adjective in -tag (< *-taka). bi and mē could still occur with these verb forms, and neither was obligatory. The core system in terms of frequency was the following:
Early New Persian Present Past Imperfective mē-raw‑ mē-raft‑ Perfective bi-raw‑ bi-raft‑ inchoat.-fut. singularity Unmarked raw‑ raft‑ gen. present gen. past Resultive-stative raft-a COP raft-a bud‑
Subsequently the system was restructured by the coalescence of the unmarked forms with the perfective forms by the fifteenth century.
- In the present, the perfective bi-form assumed distinct subjunctive function, alternating with the unmarked general present form, now opposed to the indicative present-future mē-form.
- In the past, the general unmarked form subsumed the function of the bi-form to express both general and perfective events, now opposed to the imperfective mē-past form. It thereby assumed the central role of an aorist in the resulting five-member system.
The core of the system became thus as follows, and has not changed since:
Pre-Modern, Indicative Present Past Imperfective mē-rav‑ mē-raft‑ Perfective raft‑ Resultive-stative raft-a COP raft-a bud‑
The non-indicative sub-system developed in parallel to the indicative core, using the imperfect and past-perfect forms for irreal function, and using the present subjunctive of ‘to be’ for the perfect subjective:
Pre-Modern, Non-Indicative Present Past Imperfective bi-rav‑ mē-raft‑ Perfective raft‑ Resultive-stative raft-a bāš raft-a bud‑