Verb root origin

Question

What is the origin of the roots for several conjugations, such as -ons for the imperfect.

Answer

Hi Michael - I'm not sure what you're asking. Do you mean root in the usual sense of verbs?
As in root+suffix? Or did you mean just what is the origin of the -ons suffix in the imperfect?

Answer

It's probably an obscure question so I dont mind if you don't answer it  ,I am just curious. 
For example in the imperfect the root is the 'nous' form minus 'ons' plus the imperfect endings and the subjunctive is similarly derived from the ils form. Are these types of roots just a convention or are they based on some technical or historical reason.

Answer

Oh I see.
Uff, that's a big topic. Well, those are really mnemonic devices to help memorise the forms.
Most tenses evolved directly from equivalent Latin. The preterite (passé simple) and imparfait evolved directly from Latin. The future is believed to derive from the Latin present infinitive active + present indicative active of habere. The conditional may have originated in Vulgar Latin infinitive + imperfect of habere.
Interestingly, in French the conditional is treated as a mood, whereas in Spanish the conditional is often considered a tense because the form evolved from a tense in Latin.
Hope that helps?

Answer

Thanks again Gruff. Your answer satisfies my curiosity and gives me enough to look further if I want to.