What is the rhyme scheme of Shakespeare's "Sonnet 18"? Is the poem an Elizabethan or a Petrarchan sonnet?

Let’s start with a quick review of how rhyme schemes are notated. First, we identify the final syllable in the first line of the poem, and label that sound “a”:

1. Of this World's theatre in which we stay, (a)

From now on, any line that ends in a syllable rhyming with “stay” will also be labelled “a.” Now look at line two:

2. My love like the Spectator idly sits, (b)

“Sits” doesn’t rhyme with “stay.” It’s a new sound, so we label it “b.”  From now on, any line ending in a syllable that rhymes with “sits” will also be labelled “b.”

Continue through the rest of the poem, marking each line according to its final syllable. Here’s the quatrain that we’ve just been looking at as an example:

1. Of this World's theatre in which we stay, (a)
2. My love like the Spectator idly sits, (b)
3. Beholding me, that all the pageants play, (a)
4. Disguising diversely my troubled wits. (b)

We refer to this rhyme scheme as, “A B A B.” (This is the beginning of Edmund Spenser’s Sonnet 54.)

Okay, on to your question. How do we tell the difference among various types of sonnets? Here are some clues for you.

In the Petrarchan sonnet (also known as the Italian sonnet):

• There are 14 rhyming lines


• Each line has 10 or 11 syllables, arranged in (about) five iambic feet (“da - DUM”)


• The sonnet as a whole presents two contrasting ideas, or two perspectives on one idea


• Idea #1 is usually presented in the first 8 lines of the sonnet (the octave)


• The octave has the rhyme scheme A B B A A B B A


• Idea # 2 is usually presented in the final 6 lines of the sonnet (the sestet)


• The rhyme scheme of the sestet can vary:  

             C D C D C D, or
             C D D C D C, or maybe
             C D E C D E

• The earliest writers of Petrarchan sonnets felt that it was important to avoid letting the two final lines rhyme (E E), but later poets — especially those writing in English — haven’t always followed this rule.


• At the point where one rhyme scheme gives way to the other (called the “volta”, Italian for “turn”), we see a significant change in attitude or perspective (Idea #1 shifting to Idea #2)

What about the Shakespearean sonnet?

• There are 14 rhyming lines


• Each line has 10 or 11 syllables, arranged in (about) five iambic feet (“da - DUM”)


• The sonnet as a whole presents two contrasting ideas, or two perspectives on one idea


• Idea #1 is usually presented in the first 12 lines of the sonnet (comprising 3 quatrains)


• Idea #2 is usually presented in the final 2 lines of the sonnet (a couplet)


• The rhyme scheme goes like this:


• First quatrain: A B A B


• Second quatrain: C D C D


• Third quatrain: E F E F


• Couplet: G G

Now, with all this in mind, take another look at Sonnet 18 (“Shall I compare thee . . .?”) What rhyme scheme does it have? Does it have an octave and a sestet? Does the shift in tone happen after the first 8 lines, or after the first 12 lines? Which kind of sonnet is it?

(There are other types of sonnets besides the Petrarchan and the Shakespearean, but they are two of the most important.)

Shall I compare thee to a summer's day?
Thou art more lovely and more temperate:
Rough winds do shake the darling buds of May,
And summer's lease hath all too short a date:
Sometime too hot the eye of heaven shines,
And often is his gold complexion dimm’d;
And every fair from fair sometime declines,
By chance, or nature's changing course, untrimm’d;
But thy eternal summer shall not fade
Nor lose possession of that fair thou ow’st;
Nor shall Death brag thou wander'st in his shade,
When in eternal lines to time thou grow’st;
So long as men can breathe or eyes can see,
So long lives this, and this gives life to thee.