I don't think it sounds all that plausible. I haven't seen any evidence for the idea. For it to have any credibility at all you would have to show first of all that it was a recurrent feature of all ancient languages as far back as we know.

I always assumed that it is simply connected somehow with the French name Jacques. Is Jack attested in English before the Norman conquest? Isn't it just the saxonised version of Jacques?

Last edited by The Pook; 04/29/2008 11:22 PM.