This poetic form is all about sixes. A sestina consists of six stanzas with—count 'em—six lines each, followed by a three-line stanza at the very end, known as an envoi. For those of you keeping track, that's a grand total of 39 lines.
Now here comes the fun part. Or the miserable part, depending on how much you like numbers. See, the final word of each line of the first stanza gets repeated in the lines of the subsequent stanzas, but in a different order every time. Each stanza plays off the order of the stanza that came before, so that the first line's end-word in each stanza just so happens to be the end-word of the last line of the previous stanza. Patterns, patterns everywhere.
Still with us? Awesome. We'd break it down for you even further, but we think the best way to do that is just to give you a little demo. Imagine that each end-word is represented by a letter, A-F. Now all we need is a handy chart:
Stanza 1: ABCDEF
Stanza 2: FAEBDC
Stanza 3: CFDABE
Stanza 4: ECBFAD
Stanza 5: DEACFB
Stanza 6: BDFECA
Stanza 7: It's a free for all!
If you look closely, the pattern will become pretty apparent. Think of it as a horrifyingly confusing vicious cycle. And vicious it is. Sestinas are notoriously hard to write, because you have to find your way back to each of those six words at the end of the lines. So if you choose the word spinach, for example, it might be hard for you to think of yet another thing to say about the leafy green. In other words, choose your words wisely, Shmoopoets.
Honestly, the best way to understand a sestina is to see one in action, so check out our analysis of John Ashbery's "Farm Implements and Rutabagas in a Landscape," which just so happens to use spinach as one of its end words. Leave it to John Ashbery to pull that one off.