There is a subtle difference between the is-forms and the biþ-forms in Old English. The reflexes of *h₁es-/*h₁s- typically refer to ongoing temporary states, which is not surprising, given the imperfective value of the PIE root verb. The b-forms, on the other hand, usually refer to future states or to general, timeless truths:
- Iċ bēo ġearo sōna ‘I shall be ready soon’
- On twelf mōnðum bið þrēo hund daga & V & syxtiġ daga ‘In twelve months there are 365 days’
This contrast, unique to Old English among the Germanic languages, shows that the root *bi- retained something of the perfective value of *bʰuH-. Altough it can’t reflect the unmodified root aorist, it seems reasonable to look for its origin among formations genetically connected with the aorist, and preserving an “aoristic” lexical aspect – verbs that refer to actions or states having a terminal point, evolving towards completion, or treated as a unitary whole without internal temporal structure. As mentioned in a previous post, “present” stems with a zero grade of the root and an accented *-e/o- suffix, derived from root aorists (e.g. *gʷr̥h₃-é/ó- ‘devour’ from *gʷérh₃-/*gʷr̥h₃- ‘swallow up’), fit the bill. Let us therefore suppose that *bʰuH- also generated a present stem of that type, namely *bʰuH-é/ó-, formally imperfective but with the approximate meaning ‘is going to be/become’ or ‘is (at any time, by definition)’. Such a verb is indeed attested outside Germanic, cf. Greek pʰúomai ‘grow, spring up, become’. The expected development of such a stem from PIE to PGmc. would be as follows:
1sg. *bʰuH-ṓ > *buō
2sg. *bʰuH-é-si > *buisi
3sg. *bʰuH-é-ti > *buiþi
3pl. *bʰuH-ó-nti > *buanþi
Let us suppose that the unaccented short high vowel in hiatus (resulting from the loss of the laryngeal) became a glide in pre-Germanic times, and that the resulting exotic cluster *bw- was simplified to *b already in Proto-Germanic. The predicted outcome would then be something like this:
1sg. *bō > OE *bū (or *bō?)
2sg. *bisi > OE bis(t)
3sg. *biþi > OE biþ
3pl. *banþi > OE *bœ̄þ
The first and last forms do not resemble the attested ones. But the Proto-Germanic pattern would have been so unlike anything else in the verb system that speakers could be expected to favour any “mutation” reducing its irregularity. For example, the reanalysis of *bisi and *biþi as *bi-si and *bi-þi (rather than *b-isi, *b-iþi with an aberrant asyllabic root) would have motivated the introduction of the neo-root *bi- also in the first person and the plural:
1sg. *b-ō → *bí-ō > OE bēo
3pl. *b-anþi → *bí-anþi > OE bēoþ
This restructuring could have happened at any time between late Common Germanic and archaic Old English, yielding the same outcome.
This little essay cannot exhaust the secrets of ‘to be’ in Old English. One vexing problem is the OE 2sg. eart (also Anglian (e)arþ) and the alternative plural found in the northern dialects (Mercian earun, Northumbrian aron, hence Modern English are). Their vocalism (*a, as if from pre-Gmc *o rather than *e) is puzzling and makes comparison with Old Norse ert, eru problematic. They may represent the lingering traces of another verb which has contributed to the paradigm of ‘to be’, possibly PIE *h₁er- ‘arrive’. PGmc. 2sg. *arþ(a) and 3pl. *arun(d) would make sense as reflexes of the IE perfect built to that root, retaining their stative value and interpreted as present-tense forms (‘to have arrived’ → ‘to be there’).
|Another crazy quilt (Hat tip: The Dotty One)|
I have not discussed the past tense (1/3sg. wæs, 2sg. wǣre, pl. wǣron < PGmc. *was-/*wēz-) because its origin is not controversial. Since both *h₁es- and *bʰuH- seem to have been reluctant to form perfects of their own, and since the PIE perfect was the foundation on which the new past tense of basic (non-derived) verbs was built, the missing past-tense forms were co-opted from the conjugation of the near-synonymous stem *wis-i-/*wes-a- (Gothic wisan; Old English wesan, an alternative infinitive beside bēon ‘to be’), continuing the PIE root *h₂wes- ‘stay, remain, spend the night’. The perfect of that verb became utilised as the past of ‘to be’, while the present forms just withered away (they occur sporadically in OE texts, but are extremely rare). This symbiotic relationship goes back to Proto-Germanic times, and the suppletive use of the ex-perfect stem *was-/*wēz- as ‘was/were’ occurs throughout Germanic. In Old English, we also find forms of wesan as alternative imperatives (wes/bēo ‘be’) and present participles (wesende/bēonde ‘being’). To sum up, the English paradigm of ‘to be’ is a Frankenstein monster sewn together from pieces of defective paradigms and involving perhaps as many as four different PIE roots (*h₁es- [am, is], *bʰuH- [be, being, been], *h₂wes- [was, were], and possibly *h₁er- [art, are]). A really impressive case of lexical symbiosis!