Kidsal and JoanP, I looked up the Dido reference online. It looks like there are lots of theories about it.
One article postulates the following:
"References to Dido, lover of Aeneas, in the second act of The Tempest have garnered much interpretation and speculation by readers and playgoers. Studies over the last few decades have explored Dido's role in Shakespeare's play from the intertwined perspectives of gender, colonization, empire building, and the politics of reading and rewriting classical literature.1 Although some of these have revealed the extensive use of images and themes from the Aeneid in the play and have shown especially how the love of Ferdinand and Miranda is partly parallel to, and partly a reversal of, the ancient love story of Aeneas and the queen of Carthage, there may be another motive for Dido's inclusion, a motive related to a system of wordplay involving shuffled repetitions of the sounds of letters and syllables.2 As Russ McDonald has remarked in Shakespeare's Late Style, "The notorious mystery surrounding Gonzalo's 'Widow Dido' has been examined in almost every conceivable context except, I think, that of aural identity, simple rhyme."3 Although venturing a bit beyond rhyme, this essay focuses on the name of Dido as sound, and as alphabetical letters, situating the name within a set of wordplay practices extending across the genres of drama, prose fiction, poetry, and folk ballad. It explores, therefore, an overlooked linguistic facet of Dido's multifaceted legacy.
My argument begins with anagrammatical wordplay involved in commonplace associations between desirable women and precious jewels, and Dido's participation within that complex. I then consider Dido as an emblem of love-induced madness and explore a link between her name and the nonsense words in bawdy ballads. Finally, I maintain that utterances of "widow Dido" in The Tempest echo the refrain to "Come unto these yellow sands," and therefore participate in Ariel's music, which is both alluring and cautionary. "
There is more at
http://muse.jhu.edu/journals/cdr/summary/v043/43.2.golz.htmlJoanP you say
"The audience knows that the cold porridge is "pease-porridge - a porridge made from peas. Thus the pun on Alonso's "peace" and "pease-porridge." I'd say it's a pretty good line, even if we didn't know about the pun...but it is an example of how much there is that is going right over our heads. "
So true. Almost every line contains allusions that could make a dissertation! Fortunately, Shakespeare's genius seems to be that he could include all these allusions yet make the play accessible and interesting on other levels too.