Stephen Hughes wrote:Another way to consider σύναξον, if the crossing of grammatical boundaries is a possibility, is that it might be a future imperative, but I'm not sure how that hybrid species of word would be caged in the menagerie of Greek grammatical oddities.
My mindset was wrong when I wrote this.
What was happening is not a crossing of boundaries, but rather a convergence of categories. In fact two related things were happening during our time. Let me lead you up the following two closely related garden paths ...
The first one is the convergence of the first and second aorist (indicative) endings.
The classical form of the first person singular is εἶπον, and it is the same as the third person plural. The first aorist ending for the third plural is -αν. The variant form εἶπαν is well frequently enough found in the New Testament. The difference between the third plural and the first singular form of the first aorist indicative is the non-presence of the final -ν.
Following that line of development (movement at least) of the language, the first singular form could be εἶπα. What we see in John 10:34 as Ἐγὼ εἶπα, or in the NA-UBS text in Mark 9:18 and Acts 26:15, is a result of the simplification of second aorist endings to first aorist endings.
The second is the similarity, confusion and convergence of the aorist subjunctive and the future (indicative) stems.
There are a very few examples in the New Testament of what is described as ἵνα with the future (indicative). Seen in the longer term picture - most noticeable because of the loss of a separate future form in favour of a future construction based on the imperatives in ἵνα. (A θέλω was added to the front of the construction). For many verbs there is no difference in form between the first persons singular of the future (indicative) and the aorist subjunctive. For the majority of verbs, the sigmatic stem ending of the aorist came to be the one converged form that was accepted into common usage.
For the verb συνάγω the aorist indicative forms συνῆξα (2 Esdras 7:28, 2 Esdras 8:15, 2 Esdras 17:5) and συνῆξεν (Judges B 11:20, 1 Maccabees 1:4) - with a sigmatic stem based on the classical future form συνάξω, and employing the first aorist endings in -α - are not common, but do exist.
Slightly off topic, while I feel that the ζ had a single pronunciation in Koine times I think it was the single graphical representation of two spoken forms in earlier times, the one being the -σδ- (which I thing was pronounced as -zd-) and the -γj- which was pronounced perhaps as ž, such as -σσ- from -κj- was perhaps pronounced as š. The first one results in futures in -σ- and the second in futures in -ξ-.