https://www.poetryfoundation.org/articles/145052/the-choice-of-constraint
EXTRACT
In constrained writing, one writes under a condition. That condition might mean not being allowed to do something—such as not using the letter e—or following a certain pattern. If this definition seems broad, it is. All formal writing operates under some kind of constraint; a traditional sonnet, for example, asks you to manage meter and a rhyme scheme in 14 lines. In this essay, we’ll look at less-familiar uses of constraint, ones that will challenge you in different ways. It may seem counterintuitive to put limitations on your writing, but you may find that a small constraint can make a big difference in soothing your fears of the blank page. It does so by taking some choices away and by demanding that you make new choices.
To illustrate this, I’d like to look at one of my favorite constraints—the abecedarian. Abecedarians are poems in which the first letter of each line or stanza follows the alphabet: A, then B, and so on. The abecedarian is an ancient form; it may be as old as the alphabet itself. You can find abecedarians in the Bible, though you’d have to see Psalm 119 in the original Hebrew to notice that each section is headed by a letter from the Hebrew alphabet (Aleph, Beth, Gimel …). Contemporary poets have used the alphabet constraint on a grand scale, creating long poems, such as Carolyn Forche’s “On Earth,” and even throughout entire books, such as Inger Christensen’s alphabetand Harryette Mullen’s Sleeping with the Dictionary.
How my heart sings 