Words give voice—voice to what has been, what is, what could be. Voice to what has been gained, lost, or never obtained. Voice to facts, and voice to feelings. Words are the content, but content needs form—a vehicle.
Often, prose can get the job done (and get it done pretty well). Often, prose is strong enough to carry the heavy weight of feeling and emotion. But sometimes, it’s just not. Sometimes we need something else. Sometimes we need poetry.
When the weight of profound beauty is too ethereal and transcendent and eludes our grasp, prose will not do. We need poetry.
When the pain is too brutal and raw and crushing and disorienting, prose will not do. We need poetry.
When our souls encounter what pushes against the bounds of temporal existence, and see things that are beyond what the eye can see, and feel what isn’t altogether understood within the confines of the material world, prose will not do. We need poetry.
When our hearts can’t be restrained by formalism and need the freedom of hungry, searching linguistic exploration, prose will not do. We need poetry.