It's my turn not to understand your misunderstandings, lx.
Languages arose to point to external objects and to point to mental states.
Things that existed is a clear concept.
Things that exist is also clear, but our reference to them is rather ambiguous (iteratively, actually happening now, eternal, etc.).
Thus, some grammarians speak about PAST and NON-PAST tenses. Period.
Things that don't exist yet have a "reality" problem (what if they never happen?)
Thus we can only point to them by embedding them into our "expectational" mental state, i.e., into an attitudinal stance (I am certain that, I believe that, I think it is posible that, etc.).
That we now talk about the future as a REAL tense is an effect of a misrepresentation which considers future as having the same reality as past and non-past (present, among other possibilities)
The fact that we may trace the future form to a modal construction is, I think, a clear indication of this phenomenon.
It is quite clear in English, for the main verb is accompanied by the most neutral modal verb.
This seems to happen also in some other languages, although another such modal construction is used (in Spanish, it is HAVE TO). The Italian and the French seem to be on this historical line as well. But in our case, the construction became integrated with the main verb.
In Spanish, the stem
Com -
Is attached to the infinitive ending
-er
To the present ending
-o -es -e, -emos -omeis omen
To the two past endings
-ía / -í (and the rest of the persons implicated
But the future tense is constructed with the whole infinitive
comer-
and the simplified form of the verb have
-(h)e -(h)as -(h)a -(h)emos -(h)an
The second person plural has a further development (no idea why) and instead of
comer-(h)abeis
it becomes
comer-(hab)eis
In quickly spoken Spanish in some regions of the Peninsula, you may hear sometimes
"Creo que eis ido demasiado tarde", instead of "creo que habeis ido demasiado tarde", but as i said, i have no idea whether this might be the historical reason or not.
If Daniel does not believe this, what can I say about his lack of faith?