A poem is like a gem, the saturation of a text, so complete, and being shorter than prose text, beautiful as such.
In the readers mind, while reading, it dances in unison with his own thoughts, his gathered knowledge, his word associations, his joys and sorrows.
He uses this symbiosis as a harmony, or marriage of perception, that gives his reader, a different experience, just as the poet himself, has had his own unique experience in the writing of it.