Place two lines from different poems beside each other and an unexpected conversation can begin. One image may answer the other, contradict it or make its tone suddenly comic. A cento builds a poem through that act of arrangement.
The Academy of American Poets’ glossary describes the form as a poem made entirely from lines by other poets. Its name comes from a word for patchwork, an apt image for a piece whose seams contribute to its meaning.
Keep the source attached to the line
For a private reading exercise, make a small collection of lines with the poet, poem title, edition and page or link recorded alongside each one. Move copies of the lines around rather than separating them from their source notes.
Try arranging the same material in two sequences. Read each aloud. Notice where a pronoun acquires a different apparent referent, where an image changes mood, or where a line break creates a pause that was not there before.
Your creative work is in selection and arrangement. It does not make the borrowed language your original wording.
Decide how the work will be shared
A notebook experiment and a publicly distributed poem raise different questions. Attribution matters, but credit alone does not settle permission to reproduce copyrighted lines. Before publication, check the status and terms of the material and obtain appropriate permission or advice where needed.
Public-domain work can be a practical starting point, while still requiring attention to the particular edition or translation and the rules that apply where you publish.
Give readers a clear source key rather than leaving them to recognise every borrowing. It can reveal another pleasure in the form: returning to the original poems and hearing how differently a line works in its first home. A good cento invites that return instead of hiding the route.