how can now and then be used together?

[dubiousdave]

When I was young my parents used to say `now then, stop messing about`, can anyone explain how `now` & `then` makes any sense when used together like this?

[andy-hughes]

It makes perfect sense when Jimmy Saville says it ... twice!

[MrsJo49155]

drat you beat me to it Andy!

:O)

[Quizmonster]

The point is that 'then' is not just an adverb of time meaning 'other than now', it has also been part of the phrase 'now then' for the past 1,000 years, appearing in Anglo-Saxon texts. I suppose the modern equivalent would be 'Listen up!'!
English is awash with such apparently contradictory phrases. An angry bus-conductor (are there any left?) might say to a passenger, "Come on, get off!" for example.

[andy-hughes]

Mornin' Mrs Jo49155, I must confess I was surprised to get there first, as it 'appens!

Double fab!

[jno]

then doesn't have its meaning of time in this case. Same with 'Right, then...' and 'Well, then...' It has the subsidiary meaning of in that case ('You've got the tickets? Then let's go in') and I think this is a version of that meaning.

[tigga]

but now and then, they are used together and still have the meaning of time.