A question posted today asks about the Use of “ever” in non-negated sentence, and one answer happens to mention the phrase "ever and anon." That phrase, with the meaning "occasionally or repeatedly," goes back at least as far as Shakespeare, who writes in Henry IV (act 1, scene 3):
And 'twixt his finger and his thumb he held/A pouncet-box, which ever and anon/He gave his nose, and took't away again.
But did "ever and anon" always carry this meaning? The meaning isn't intuitively obvious to me from its components because, in this setting, I think of ever as meaning "always" (though in other situations it can mean "at least once") and anon as meaning "soon" or "later." If not, what was the original meaning of the phrase? If so, how did it emerge from the separate meanings of ever and anon?