I hope you can see from this layout that the form is actually not as convoluted as it sounds. Describing how a villanelle works is a great deal more linguistically challenging than writing one. Mahon, by the way, as is permissible, has slightly altered the refrain line, in his case turning the direct speech of the first refrain. There are no rules as to metre or length of measure, but the rhyming is important. Slant-rhyme versions exist but for my money the shape, the revolving gavotte of the refrains and their final coupling, is compromised by partial rhyming. The form is thought to have evolved from Sicilian round songs, of the ‘London Bridge is falling down’ variety. In the anthologies you will find villanelles culled from the era of their invention, the sixteenth century, especially translations of the work of the man who really got the form going, the French poet Jean Passerat: after these examples there seems to be a notable lacuna until the late nineteenth century. Oscar Wilde wrote ‘Theocritus’, a rather mannered neo-classical venture–‘O singer of Persephone!/Dost thou remember Sicily?’ (I think it best to refer to villanelles by their refrain lines), while Ernest Dowson, Wilde’s friend and fellow
But it is, perhaps surprisingly, during the twentieth century that the villanelle grows in popularity; besides those we have seen by Mahon and Dylan Thomas, there are memorable examples you may like to try to get hold of by Roethke, Auden, Empson, Heaney, Donald Justice, Wendy Cope and a delightful comic one candidly wrestling with the fiendish nature of the form itself entitled ‘Villanelle of Ye Young Poet's First Villanelle to his Ladye and Ye Difficulties Thereof’ by the playwright Eugene O’Neill: ‘To sing the charms of Rosabelle,/I tried to write this villanelle.’ But for a reason I cannot quite fathom it is
A form that seemed so dead in the seventeenth, eighteenth and nineteenth centuries brought back to rude and glistening health in the twentieth and twenty-first. Why? The villanelle has been called ‘an acoustic chamber for words’ and a structure that lends itself to ‘duality, dichotomy, and debate’, this last assertion from ‘Modern Versions of the Villanelle’ by Philip Jason, who goes on to suggest:there is even the potential for the two repeating lines to form a paradigm for schizophrenia…the mind may not fully know itself or its subject, may not be in full control, and yet it still tries, still festers and broods in a closed room towards a resolution that is at least pretended by the final couplet linking of the refrain lines.