The doctrine of the affections is key to understanding the music (and the poetry) of Baroque opera.
Each aria is expressing a single emotion (or different facets of that same emotion).
This derives from Ancient Greek theory so fits right in with the Florentine Camerata's ideas about Ancient Greece that led to Peri's Dafne and Euridice, and eventually Monteverdi's Orfeo, and thence modern opera.
The application of the doctrine creates stylised poetry and stylised music, and would have been understood as such.
If you have a production that is not 'in tune' with this approach, I'd hazard a guess that you're going to end up with something a bit wonky.

Later Baroque opera suffers a little from over-stylisation, perhaps sometimes to the extent of calcification. Virtuosity, not necessarily directly connected to the affect being expressed, begins to dominate the drama. It is easy for the drama to become secondary to the music (ironic, since the seconda pratica began with an emphasis on text over music, and the seconda pratica is regarded by most historians as the genesis of the Baroque period). Perhaps it is a victim of its own success. As opera became more popular, it moved out of the court and into the public theatre. In the public theatre, there were a greater proportion of audience members without the familiarity with poetic and musical theory, or with mythology (as SH has pointed out in his really very thought-provoking post), and therefore the emphasis almost has to move away from the aspects that were deeply important to early opera. When Gluck seeks to reinvent opera, he goes back to the Ancient Greeks in his attempt to make a more 'natural' theatre, but one could say that it's really John Gay's Beggar's Opera that defines the trajectory of Classical opera towards the end of the 18th century - an opera for the people. I suppose it's possible to say that English composers like Purcell had been tending towards that anyway with their rather approximate retellings of mythology (e.g. Dido and Aeneas) and relaxed attitudes towards theory and practice.

This is probably all a bit garbled.

Thank you SH and hh for two very informative posts.

Can I second Ollie's request for recommended recordings from our Baroque experts?

Oh good. I'm not completely on me todd then.

It is, yes. (I can't find my edition of Jonson's plays. They are behind something which is in front of something else but what it is they are behind which is in front of what I do not know off-hand. My books & CDs are not well organised. Neither is their owner).

Jonson's annotations are to the 1st quarto. People said look at him, showing off, pretending plays are serious things & he has a classical education. He then defended the annotations & his classical education as returning tragedy to Senecan dignity. Whatever that would be when it was at home.

Sejanus, his fall got Jonson charged with treason in 1605 - and plot & probably gunpowder, too. So it all rather galloped beyond theory. Many years since I've read it.

I like Jonson's poems a lot. I can find my edition of those

Not at all!

And I also would like to thank hh and SH (you're not related are you?) for their fascinating thoughts. This from somebody who is sadly at the moment experiencing a what's-it-all-about detachment from baroque opera, I can't really seem to engage with it at all (the opposite is true of the non-operatic stuff), but reading through a thread like this certainly helps waft me back in the right direction.

IIRC also has a rather fun Cérémonie des Turcs.

I suppose it would have to be the Passions, except there the slippage is in the fact that they're not operas rather than the fact that he didn't write them which unless an awful lot of people are very mistaken indeed he did... 

I have just listened again to Catherine Bott's introduction to the broadcast of La Calisto.

From her desciption of the production, I can see what SH means about unnecessary camp.  It may have worked but I could have found it rather irritating.

What I said was that baroque operas can seem camp to us.  And by camp, I didn't mean calling for outrageous productions, I meant the artificiality.

I must say that an awful lot of movies (including every musical I've ever seen) are pretty camp in my mind, and not necessarily the worse than that.