Our community blogs
If the word is the cornerstone of poetry, the line is it's foundation. The line is the fundamental element of verse, the difference between verse and prose. Its purpose is to increase the density of the thought or image and give focus to the words. The line is written in many styles, patterns and meters.
I recently discovered this article by Dana Gioia on the poetic line which prompted this blog. After reading it I realized I cannot improve on it. It says it all, I encourage you to read it. The Poetic Line . Dana Gioia is Former Chairman of the National Endowment for the Arts, an award winning poet and is currently the Poet Laureate of California.
As a side note, indentation of the line and/or centering the poem on the page is at the poet's discretion. Indenting a line midway or at the end of a stanza can give emphasis to the line. Sometimes centering a poem can enhance the content by the visual positioning. However in my opinion, all too often centering a poem is used as a gimmick to distract from the lack of substance. It should compliment the content otherwise keep lines at left margin.
For further information about some of the more common poetic lines you can also go to The Frame.