I was reading the first chapter of Ian Davidson's "Ideas of Space in Contemporary Poetry" yesterday. It made the point that collage is probably the 20th Century's main contribution to avant garde technique. Introduced by the Cubists in the period 1911-13, then taken up by Dadaists, Surrealists, installation artists and all manner of modern artists, it's almost become part of the atmosphere of contemporary visual art.
It's also been a part of modernist poetry and non-mainstream poetry right from the off. From T S Eliot, Ezra Pound, William Carlos Williams, Zukovsky and many Dadaist poets, through to the present day poets like Tony Lopez, who use it as a large part of their practice.
For me, it's become almost second nature. I'm either cutting up my own words, or cutting up articles from newspapers, writing down and rearranging overheard conversations, mixing in slogans from shop windows, flarfing (using phrases from webpages) or making use of found material.
The effect of this is to attempt to get away from the chronological, to the poem as a kind of field, in which interesting encounters of sound, meaning and image can be found. It also - hopefully - helps to reader to complete the poem for themselves. The number of possible meanings is increased; but none of the meanings are complete, and all are subject to uncertainty.
Collage is paratactic: it puts things side by side to see how they feel together. It juxtaposes, it disturbs settled orders, it creates coincidences and relationships between things and words that weren't there before. It can shift register sometimes mid-sentence, burst out in all directions, imitate the semiotic overload of contemporary culture, confuse and dazzle.
Finally, here's Tristan Tzara's instructions on writing poetry:
TO MAKE A DADAIST POEM
Take a newspaper.
Take some scissors.
Choose from this paper an article the length you want to make your poem.
Cut out the article.
Next carefully cut out each of the words that make up this article and put them all in a bag.
Next take out each cutting one after the other.
Copy conscientiously in the order in which they left the bag.
The poem will resemble you.
And there you are - an infinitely original author of charming sensibility, even though unappreciated by the vulgar herd.