It’s true that a poem can be attempted in brief interstitial moments, pulled out of the pocket and worked on while waiting for a bus or riding a train or while children nap or while waiting for a new batch of clerical work or blood samples to come in. But only certain kinds of poems are amenable to these conditions. Sometimes the very knowledge of coming interruption dampens the flicker.
Adrienne Rich, “How Does a Poet Put Bread on the Table?” (1993); The Norton Introduction to Literature (shorter 8th ed.), ed. Jerome Beaty et al. (New York: Norton, 2002), 859.