I start with that sentence to remind you that everything I'm trying to explain in these threads is based on what poets do, not on what you or anybody else is supposed to do. With that said, over the years, people have offered descriptions and called them rules. Then someone comes along and breaks them and this is the key point:
It still sounds right.
Or maybe it doesn't sound "right" but it still sounds "good".
And that's what matters. It should also be pointed out that people will have different opinions on the subject (and of course most will have no opinion at all). Some will be more "conservative" (the closer to the metrical grid, the better), some will be more "liberal" (the farther away from the metrical grid, the better), and some will wonder why the hell people are actually talking about these things.
Dana Gioia:
--from "Meter-Making Arguments", Meter in English, p. 75Literary etiquette demands that in mixed company poets pretend prosody is a dull subject. What genuine artist could possibly take those dusty Greek terms and mechanistic scansions seriously? Only pedants reduce art to arithmetic. Among their own kind, however, poets find prosody anything but boring. I have watched poets argue intemperately over a detail of scansion and witnessed others exhaust an evening disputing theories of versification. Free-verse poets display surprisingly little immunity from these fevers; no one, after all, likes to debate religion more than an atheist.
With these ideas in mind, let's get started:
Substitution 1: the extra-metrical syllable
The most common variation of the pentameter line or of any line is the extra-metrical syllable:
u-S, u-S, u-S, u-S, u-S (u)
It makes sense, doesn't it? Why limit yourself to words that are stressed only on the last syllable or are monosyllabic? What's more at least the way I read it, it doesn't influence the 'feel' of the pentameter line. When I read these line out loud, I feel the line is completed at the final stress and that last syllable is simply added. This is why I use extra-metrical, it just doesn't seem a part of the overall feel of the meter, it feels outside of it.
Examples:
--Dryden, All for LoveI'll not be pleased with less than Cleopatra
--Adrienne Rich, "Living in Sin"She woke sometimes to feel the daylight coming
--Charles Martin, "Easter Sunday, 1985"The age of miracles is gone forever
--Robert B. Shaw, "Narcissus" *What it would take, a magic word to free you
The age of miracles is gone forever
What would it take, a magic word to free you
Other terms you'll see that mean the same thing:
hypermetrical ending
feminine ending (Masculine is ending on the stress. The same words are used for rhyme as well)
extra-syllable ending (es-ending)
amphibrachic foot, amphibrach (u-S-u)
--the problem with this word (another one of those dusty Greek terms) is that it gives the impression you can put extra syllables anywhere in the line. If you do that, you start losing the specific iambic cadence. Keep it as a special case, at the end of the line.
In theory, you can actually get away with two unstressed syllables at the end but I'll leave that for later. The examples I've seen aren't so much outside the meter as metrically ambiguous.
And just to confuse you more, this substitution does seem to take on a life of its own here:
--Sonnet 87
Farewell! thou art too dear for my possessing,
And like enough thou know'st thy estimate,
The charter of thy worth gives thee releasing;
My bonds in thee are all determinate.
For how do I hold thee but by thy granting?
And for that riches where is my deserving?
The cause of this fair gift in me is wanting,
And so my patent back again is swerving.
Thy self thou gavest, thy own worth then not knowing,
Or me to whom thou gav'st it else mistaking;
So thy great gift, upon misprision growing,
Comes home again, on better judgement making.
Thus have I had thee, as a dream doth flatter,
In sleep a king, but waking no such matter.
*The above lines are all taken from Steele again, p. 64. This type of ending is not difficult to find however. Pretty much anywhere you look you'll see it. I was being lazy -- again.